<?php
/*
 * Plugin Name: Replace og:image .avif to .jpg
 * Description: Replaces og:image URLs ending in -jpg.avif with .jpg in the page output.
 */

add_action(
	'template_redirect',
	function() {
    	ob_start( 'joost_replace_og_image_avif_with_jpg' );
	}
);

function joost_replace_og_image_avif_with_jpg( $buffer ) {
    // Replace "-jpg.avif" with ".jpg" in og:image meta tags.
    return preg_replace('/(<meta\s+property="og:image"\s+content="[^"]+)-jpg\.avif(")/i', '$1.jpg$2', $buffer);
}