I had a custom 404 error page configured per the guidance at https://www.joomshaper.com/blog/create-a-custom-joomla-404-page-with-sp-page-builder, but after update Pagebuilder to 5.5.0, I now get the same "Dynamic Content" message you are reporting.
I checked my Joomla root directory > templates > shaper_helixultimate > error.php file, and see that the custom 404 code is gone. The SppB update must have replaced the error.php file with a default.
I reconfigured the error.php file, but still only get the "Dynamic Content" property page. Maybve the custom 404 page guidance no longer works. See https://www.certifiedinfosec.com/zdfgh.
Joomshaper? Help?