<?php

function cwpai_disable_gutenberg_for_certain_post_types($can_edit, $post_type) {
    if ($post_type !== 'post') {
        return false;
    }
    return $can_edit;
}
add_filter('use_block_editor_for_post_type', 'cwpai_disable_gutenberg_for_certain_post_types', 10, 2);