Block editor not displaying properly

So the block editor is not displaying properly. Just plain text, no styling, and no actual editor when I go into the page/post editor (this also applies to custom post types). I am running the latest version of WordPress, 5.4. This happened briefly on the test server, but went away on its own so I pushed to the live site. It’s back again and I don’t know why or how to fix it. I CAN, however, workaround it by using the Classic Editor plugin. But even this is causing another problem, as some users are seeing the Classic Editor, and some are seeing the glitched out Blocks editor (this probably deserves a separate question in its own right, as we’ve exhausted the usual “clear the cache and reload the site” approaches).

The broken Blocks editor

The biggest hiccups I can think of came during the restoration process. The site I’m working on was transferred between hosts recently, and I used All-in-One WP migration to backup and transfer the site. While this plugin worked in the past, it appears a recent update broke it, and so I had to use an older version (version 6.77, verses the current version, 7.20) to restore the site. Is there any reason to believe that this older version can’t handle newer versions of WordPress? I also had to edit these values in the php.ini file, while trying to restore the backup:

Here’s a list of the plugins currently running on the site for reference:

A list of plugins on the site