plugin prevents iframe editor from loading

WordPress is implementing a new editor style for the WP admin which uses an iframe instead of embedding directly in the page.
https://make.ww.wp.xz.cn/core/2025/11/12/preparing-the-post-editor-for-full-iframe-integration/

For some reason, this plugin prevents the iframe editor from loading.

Steps to recreate:

1. Create a fresh WP site (this can be done easily here: https://playground.wordpress.net/)
2. Open a post or page in the editor
3. inspect the markup, note there’s an iframe with the name editor-canvas which the content is loaded in
4. Install the plugin + activate
5. Go back to the same page and check the markup again. See that the iframe for editor-canvas is gone.