diff --git a/src/wp-includes/media.php b/src/wp-includes/media.php
index dd98b5e622..335e415798 100644
--- a/src/wp-includes/media.php
+++ b/src/wp-includes/media.php
@@ -5652,13 +5652,9 @@ function wp_get_loading_optimization_attributes( $tag_name, $attr, $context ) {
 	 * can result in the first post content image being lazy-loaded or an image further down the page being marked as a
 	 * high priority.
 	 */
-	switch ( $context ) {
-		case 'the_post_thumbnail':
-		case 'wp_get_attachment_image':
-		case 'widget_media_image':
-			if ( doing_filter( 'the_content' ) ) {
-				return $loading_attrs;
-			}
+	// TODO: Handle shortcode images together with the content (see https://core.trac.wordpress.org/ticket/58853).
+	if ( 'the_content' !== $context && 'do_shortcode' !== $context && doing_filter( 'the_content' ) ) {
+		return $loading_attrs;
 	}
 
 	/*
@@ -5709,64 +5705,56 @@ function wp_get_loading_optimization_attributes( $tag_name, $attr, $context ) {
 	}
 
 	if ( null === $maybe_in_viewport ) {
-		switch ( $context ) {
-			// Consider elements with these header-specific contexts to be in viewport.
-			case 'template_part_' . WP_TEMPLATE_PART_AREA_HEADER:
-			case 'get_header_image_tag':
-				$maybe_in_viewport    = true;
-				$maybe_increase_count = true;
-				break;
-			// Count main content elements and detect whether in viewport.
-			case 'the_content':
-			case 'the_post_thumbnail':
-			case 'do_shortcode':
-				// Only elements within the main query loop have special handling.
-				if ( ! is_admin() && in_the_loop() && is_main_query() ) {
-					/*
-					 * Get the content media count, since this is a main query
-					 * content element. This is accomplished by "increasing"
-					 * the count by zero, as the only way to get the count is
-					 * to call this function.
-					 * The actual count increase happens further below, based
-					 * on the `$increase_count` flag set here.
-					 */
-					$content_media_count = wp_increase_content_media_count( 0 );
-					$increase_count      = true;
+		$header_enforced_contexts = array(
+			'template_part_' . WP_TEMPLATE_PART_AREA_HEADER => true,
+			'get_header_image_tag'                          => true,
+		);
 
-					// If the count so far is below the threshold, `loading` attribute is omitted.
-					if ( $content_media_count < wp_omit_loading_attr_threshold() ) {
-						$maybe_in_viewport = true;
-					} else {
-						$maybe_in_viewport = false;
-					}
-				}
-				/*
-				 * For the 'the_post_thumbnail' context, the following case
-				 * clause needs to be considered as well, therefore skip the
-				 * break statement here if the viewport has not been
-				 * determined.
-				 */
-				if ( 'the_post_thumbnail' !== $context || null !== $maybe_in_viewport ) {
-					break;
-				}
-			// phpcs:ignore Generic.WhiteSpace.ScopeIndent.Incorrect
-			// Consider elements before the loop as being in viewport.
-			case 'wp_get_attachment_image':
-			case 'widget_media_image':
-				if (
-					// Only apply for main query but before the loop.
-					$wp_query->before_loop && $wp_query->is_main_query()
-					/*
-					 * Any image before the loop, but after the header has started should not be lazy-loaded,
-					 * except when the footer has already started which can happen when the current template
-					 * does not include any loop.
-					 */
-					&& did_action( 'get_header' ) && ! did_action( 'get_footer' )
-				) {
-					$maybe_in_viewport    = true;
-					$maybe_increase_count = true;
-				}
-				break;
+		/**
+		 * Filters the header-specific contexts.
+		 *
+		 * @since 6.4.0
+		 *
+		 * @param array $default_header_enforced_contexts Map of contexts for which elements should be considered
+		 *                                                in the header of the page, as $context => $enabled
+		 *                                                pairs. The $enabled should always be true.
+		 */
+		$header_enforced_contexts = apply_filters( 'wp_loading_optimization_force_header_contexts', $header_enforced_contexts );
+
+		// Consider elements with these header-specific contexts to be in viewport.
+		if ( isset( $header_enforced_contexts[ $context ] ) ) {
+			$maybe_in_viewport    = true;
+			$maybe_increase_count = true;
+		} elseif ( ! is_admin() && in_the_loop() && is_main_query() ) {
+			/*
+			 * Get the content media count, since this is a main query
+			 * content element. This is accomplished by "increasing"
+			 * the count by zero, as the only way to get the count is
+			 * to call this function.
+			 * The actual count increase happens further below, based
+			 * on the `$increase_count` flag set here.
+			 */
+			$content_media_count = wp_increase_content_media_count( 0 );
+			$increase_count      = true;
+
+			// If the count so far is below the threshold, `loading` attribute is omitted.
+			if ( $content_media_count < wp_omit_loading_attr_threshold() ) {
+				$maybe_in_viewport = true;
+			} else {
+				$maybe_in_viewport = false;
+			}
+		} elseif (
+			// Only apply for main query but before the loop.
+			$wp_query->before_loop && $wp_query->is_main_query()
+			/*
+			 * Any image before the loop, but after the header has started should not be lazy-loaded,
+			 * except when the footer has already started which can happen when the current template
+			 * does not include any loop.
+			 */
+			&& did_action( 'get_header' ) && ! did_action( 'get_footer' )
+			) {
+			$maybe_in_viewport    = true;
+			$maybe_increase_count = true;
 		}
 	}
 
diff --git a/tests/phpunit/tests/media.php b/tests/phpunit/tests/media.php
index ebd2f767e1..f90378b111 100644
--- a/tests/phpunit/tests/media.php
+++ b/tests/phpunit/tests/media.php
@@ -4301,15 +4301,6 @@ EOF;
 			// Set as main query.
 			$this->set_main_query( $query );
 
-			/*
-			 * For contexts other than for the main content, still return 'lazy' even in the loop
-			 * and in the main query, and do not increase the content media count.
-			 */
-			$this->assertSame(
-				array( 'loading' => 'lazy' ),
-				wp_get_loading_optimization_attributes( 'img', $attr, 'wp_get_attachment_image' )
-			);
-
 			// First three element are not lazy loaded. However, first image is loaded with fetchpriority high.
 			$this->assertSame(
 				array( 'fetchpriority' => 'high' ),
@@ -4339,6 +4330,184 @@ EOF;
 		}
 	}
 
+	/**
+	 * Tests that wp_get_loading_optimization_attributes() returns fetchpriority=high and increases the count for arbitrary contexts in the main loop.
+	 *
+	 * @ticket 58894
+	 *
+	 * @covers ::wp_get_loading_optimization_attributes
+	 *
+	 * @dataProvider data_wp_get_loading_optimization_attributes_arbitrary_contexts
+	 *
+	 * @param string $context Context for the element for which the loading optimization attribute is requested.
+	 */
+	public function test_wp_get_loading_optimization_attributes_with_arbitrary_contexts_in_main_loop( $context ) {
+		$attr = $this->get_width_height_for_high_priority();
+
+		$this->assertSame(
+			array( 'loading' => 'lazy' ),
+			wp_get_loading_optimization_attributes( 'img', $attr, $context ),
+			'The "loading" attribute should be "lazy" when not in the loop or the main query.'
+		);
+
+		$query = $this->get_new_wp_query_for_published_post();
+
+		// Set as main query.
+		$this->set_main_query( $query );
+
+		while ( have_posts() ) {
+			the_post();
+
+			$this->assertSame(
+				array( 'fetchpriority' => 'high' ),
+				wp_get_loading_optimization_attributes( 'img', $attr, $context ),
+				'The "fetchpriority" attribute should be "high" while in the loop and the main query.'
+			);
+
+			// Images with a certain minimum size in the arbitrary contexts of the page are also counted towards the threshold.
+			$this->assertSame( 1, wp_increase_content_media_count( 0 ), 'The content media count should be 1.' );
+		}
+	}
+
+	/**
+	 * Tests that wp_get_loading_optimization_attributes() does not return lazy loading attributes when arbitrary contexts are used before the main query loop.
+	 *
+	 * @ticket 58894
+	 *
+	 * @covers ::wp_get_loading_optimization_attributes
+	 *
+	 * @dataProvider data_wp_get_loading_optimization_attributes_arbitrary_contexts
+	 *
+	 * @param string $context Context for the element for which the loading optimization attribute is requested.
+	 */
+	public function test_wp_get_loading_optimization_attributes_with_arbitrary_contexts_before_main_query_loop( $context ) {
+		$attr = $this->get_width_height_for_high_priority();
+
+		$query = $this->get_new_wp_query_for_published_post();
+
+		// Set as main query.
+		$this->set_main_query( $query );
+
+		$this->assertSame(
+			array( 'loading' => 'lazy' ),
+			wp_get_loading_optimization_attributes( 'img', $attr, $context ),
+			'The "loading" attribute should be "lazy" before the main query loop.'
+		);
+
+		while ( have_posts() ) {
+			the_post();
+
+			$this->assertSame(
+				array( 'fetchpriority' => 'high' ),
+				wp_get_loading_optimization_attributes( 'img', $attr, $context ),
+				'The "fetchpriority" attribute should be "high" while in the loop and the main query.'
+			);
+
+			$this->assertArrayNotHasKey(
+				'loading',
+				wp_get_loading_optimization_attributes( 'img', $attr, $context ),
+				'No "loading" attribute should be present on the second image in the main query loop.'
+			);
+		}
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array[]
+	 */
+	public function data_wp_get_loading_optimization_attributes_arbitrary_contexts() {
+		return array(
+			array( 'wp_get_attachment_image' ),
+			array( 'something_completely_arbitrary' ),
+		);
+	}
+
+	/**
+	 * Tests that wp_get_loading_optimization_attributes() returns empty array for arbitrary context.
+	 *
+	 * @ticket 58894
+	 *
+	 * @covers ::wp_get_loading_optimization_attributes
+	 */
+	public function test_wp_get_loading_optimization_attributes_should_return_empty_array_for_any_arbitrary_context() {
+		remove_all_filters( 'the_content' );
+
+		$result = null;
+		add_filter(
+			'the_content',
+			function( $content ) use ( &$result ) {
+				$attr   = $this->get_width_height_for_high_priority();
+				$result = wp_get_loading_optimization_attributes( 'img', $attr, 'something_completely_arbitrary' );
+				return $content;
+			}
+		);
+		apply_filters( 'the_content', '' );
+
+		$this->assertSame( array(), $result );
+	}
+
+	/**
+	 * @ticket 58894
+	 *
+	 * @covers ::wp_get_loading_optimization_attributes
+	 *
+	 * @dataProvider data_wp_get_loading_optimization_attributes_header_context
+	 *
+	 * @param string $context The context for the header.
+	 */
+	public function test_wp_get_loading_optimization_attributes_header_contexts( $context ) {
+		$attr = $this->get_width_height_for_high_priority();
+
+		$this->assertArrayNotHasKey(
+			'loading',
+			wp_get_loading_optimization_attributes( 'img', $attr, $context ),
+			'Images in the header context should not be lazy-loaded.'
+		);
+
+		add_filter( 'wp_loading_optimization_force_header_contexts', '__return_empty_array' );
+
+		$this->assertSame(
+			array( 'loading' => 'lazy' ),
+			wp_get_loading_optimization_attributes( 'img', $attr, $context ),
+			'Images in the header context should get lazy-loaded after the wp_loading_optimization_force_header_contexts filter.'
+		);
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array[]
+	 */
+	public function data_wp_get_loading_optimization_attributes_header_context() {
+		return array(
+			array( 'template_part_' . WP_TEMPLATE_PART_AREA_HEADER ),
+			array( 'get_header_image_tag' ),
+		);
+	}
+
+	/**
+	 * @ticket 58894
+	 *
+	 * @covers ::wp_get_loading_optimization_attributes
+	 */
+	public function test_wp_loading_optimization_force_header_contexts_filter() {
+		$attr = $this->get_width_height_for_high_priority();
+
+		add_filter(
+			'wp_loading_optimization_force_header_contexts',
+			function( $context ) {
+				$contexts['something_completely_arbitrary'] = true;
+				return $contexts;
+			}
+		);
+
+		$this->assertSame(
+			array( 'fetchpriority' => 'high' ),
+			wp_get_loading_optimization_attributes( 'img', $attr, 'something_completely_arbitrary' )
+		);
+	}
+
 	/**
 	 * Tests that wp_get_loading_optimization_attributes() returns the expected loading attribute value before loop but after get_header if not main query.
 	 *