allow iframe tags in ACF field

code-snippet.php

<?php

/* allow iframe tags */

add_filter( 'wp_kses_allowed_html', 'acf_add_allowed_iframe_tag', 10, 2 );
function acf_add_allowed_iframe_tag( $tags, $context ) {

	if ( $context === 'post' ) {
			
			$tags['iframe'] = array(
				'src'             => true,
				'height'          => true,
				'width'           => true,
				'frameborder'     => true,
				'allowfullscreen' => true,
			);
    
		}

    return $tags;
}