Paste gist.github.com URL in Gutenberg -> get the embed [WordPress]

gists_in_gutenberg.php

//Important: When adding a gist link in Editor you MUST choose - convert to link, not Embed!			
//Embed Gists to be displayed in Gutenberg without plugin, works on new and existing ones



add_filter( 'render_block', 'sz_embed_gists_in_gutenberg_block', 10, 2 );
function sz_embed_gists_in_gutenberg_block( $block_content, $block ) {
	// Check if the block is a paragraph block
	if ( $block['blockName'] !== 'core/paragraph' ) {
		return $block_content;
	}

	if ( empty( $block_content ) ) {
		return $block_content;
	}

	$dom = new DOMDocument;
	libxml_use_internal_errors( true );

	// Load the block content into the DOMDocument
	$dom->loadHTML( $block_content, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD );
	// Get all paragraphs
	$paragraphs = $dom->getElementsByTagName( 'p' );

	$domElemsToTarget = array();

	foreach ( $paragraphs as $paragraph ) {
		$paragraph_content = $paragraph->nodeValue;
		if ( strpos( $paragraph_content, "gist.github.com" ) !== false ) {
			$domElemsToTarget[] = $paragraph;
		}
	}

	foreach ( $domElemsToTarget as $domElement ) {
		// In case it's a link to a specific file inside the gist:
		$p_content  = $domElement->nodeValue;
		$url_string = explode( '#', $p_content );
		// Create script link
		$link                 = $dom->createElement( 'script' );
		$specific_file_string = ( ! empty( $url_string[1] ) ) ? "?" . preg_replace( [
				'/^file-/',
				'/-php$/'
			], [ 'file=', '.php' ], $url_string[1] ) : '';
		$link->setAttribute( 'src', $url_string[0] . ".js" . $specific_file_string );
		// Wrap it in <p> (for some reason, <script> that goes just after the <h> tag without wrapper gets missed out)
		$p_new = $dom->createElement( 'p' );
		$p_new->setAttribute( "class", "gist-embed-php" );
		$p_new->appendChild( $link ); // Nest it
		$domElement->parentNode->replaceChild( $p_new, $domElement );
	}

	// Save and return the modified HTML block content, extracting the body content

	$block_content = $dom->saveHTML();

	return $block_content;
}

//This doesn't work as fro Gutenberg plugin 18.4 (maybe earlier), we need to use render_block instead, keepinmg for reference
add_filter( 'the_content', 'sz_embed_gists_in_gutenberg' );
function sz_embed_gists_in_gutenberg( $content ) {
	if(empty($content)) return;
	$dom = new DOMDocument;
	libxml_use_internal_errors(true);
    $content = mb_convert_encoding($content, 'HTML-ENTITIES', "UTF-8"); 
	$dom->loadHTML($content);
	$paragraphs = $dom->getElementsByTagName('p');
	$domElemsToTarget = array();
		foreach ( $paragraphs as $paragraph ) {
				$paragraph_content = $paragraph->nodeValue;
				if (strpos($paragraph_content, "gist.github.com") !== false) {
					$domElemsToTarget[] = $paragraph;
				}
		}
	foreach( $domElemsToTarget as $domElement ){
		//in case it's a link to a specific file inside the  gist:		
		$p_content = $domElement->nodeValue;
		$url_string = explode('#',$p_content);
		//create link
		$link = $dom->createElement('script');
		$specific_file_string = (!empty($url_string[1])) ? "?".preg_replace(['/^file-/','/-php$/'],['file=','.php'],$url_string[1]) : ''; 		
		$link->setAttribute('src', $url_string[0].".js".$specific_file_string);
		//wrap it in <p> (for some reason, <script> that goes just after the <h> tag without wrapper gets missed out)
		$p_new = $dom->createElement('p');
		$p_new->setAttribute("class", "gist-embed-php");
		$p_new->appendChild($link); //nest it		
		
		$domElement->replaceWith($p_new);
		/** For PHP < 8
		//remove initial contents of the paragraph		
		while ($domElement->hasChildNodes()) {
		   $domElement->removeChild($domElement->firstChild);
		 }
		//append the new one
		$domElement->appendChild($p_new);
		**/	
	}
	$content= $dom->saveHtml();
	return $content;
}

This is not working since recently. We need to used render_block filter instead