Moving servers breaks css loading

I’m having some bizzare problems moving a site I made in Frost to a new url. For some reason certain styles in the blocks aren’t loading on the front end. But the site works just fine on the back-end. In particular, the Cover Blocks and the Layout blocks and featured images are missing CSS.

I tried importing and exporting databases and files using all the tools I normally use with no problems and disabling all plugins. I don’t even see anything in the logs showing files being blocked by security, wrong urls, or missing files! The CSS just seems to be missing – yet it’s loading fine in the gutenberg back-end editor.

I’ve never had this problem before except with the frost block theme. This is the second site it happened with. But Frost is the only block theme I’ve ever tried so maybe I missed something important when migrating a site?