You need to use get_the_post_thumbnail_url
(the one you’re using echo
‘s the URL).
get_the_post_thumbnail( $the_post_id, 'medium', [
'data-zoom-image' => get_the_post_thumbnail_url( $the_post_id, 'full' ),
]);
You need to use get_the_post_thumbnail_url
(the one you’re using echo
‘s the URL).
get_the_post_thumbnail( $the_post_id, 'medium', [
'data-zoom-image' => get_the_post_thumbnail_url( $the_post_id, 'full' ),
]);