Closes #6312: Exclude youtube thumbnail from lazyload

inc/Dependencies/RocketLazyload/Iframe.php

@@ -49,7 +49,7 @@ public function lazyloadIframes( $html, $buffer, $args = [] ) {
 				continue;
 			}
 
-			if ( $args['youtube'] ) {
+			if ( $args['youtube'] && ! $this->is_youtube_excluded( $iframe ) ) {
 				$iframe_lazyload = $this->replaceYoutubeThumbnail( $iframe );
 			}
 
@@ -234,4 +234,27 @@ public function cleanYoutubeUrl( $url ) {
 
 		return $scheme . $host . $path;
 	}
+
+	/**
+	 * Checks if a youtube thumbnail is excluded from lazyload.
+	 *
+	 * @param array $iframe Array of matched patterns.
+	 * @return boolean
+	 */
+	private function is_youtube_excluded( array $iframe ): bool {
+		/**
+		 * Filters the patterns excluded from lazyload for youtube thumbnails.
+		 *
+		 * @param array $excluded_patterns Array of excluded patterns.
+		 */
+		$excluded_patterns = apply_filters( 'rocket_lazyload_exclude_youtube_thumbnail', [] );
+
+		foreach ( $excluded_patterns as $excluded_pattern ) {
+			if ( strpos( $iframe[0], $excluded_pattern ) !== false ) {
+				return true;
+			}
+		}
+
+		return false;
+	}
 }