try change in file vendor/magento/module-page-builder/view/adminhtml/web/template/page-builder.html tag iframe in sandbox attribute: if you have only allow-scripts add just allow-same-origin by patch. Works for me in 2.4.6-p10

<iframe attr="id: 'render_frame_' + id" sandbox="allow-scripts allow-same-origin" style="position: absolute; width:0; height:0; border: none;"></iframe>

If for some reasons it doesn't work try apply this whole patch https://drive.google.com/file/d/1NCOaxO7sKc7wkIEWtrWCx-uJlnAvzw2P/view proposed in this question https://magento.stackexchange.com/questions/373475/magento-2-4-7-page-builder-was-rendering-for-5-seconds-without-releasing-locks