Block apiVersion

Yes, there is the message I see in the dev tools console in a Firefox browser (if that matters)

Block with API version 2 or lower is deprecated since version 6.9. See: https://developer.ww.wp.xz.cn/block-editor/reference-guides/block-api/block-api-versions/block-migration-for-iframe-editor-compatibility/ Note: The block “petersplugins/the-url” is registered with API version 2. This means that the post editor may work as a non-iframe editor. Since all editors are planned to work as iframes in the future, set the apiVersion field to 3 and test the block inside the iframe editor.