Common causes

The $map variable is not initialized properly or is overwritten by a non-map value.

A custom module or theme may have modified the Sass variable incorrectly.

Removing the database may cause some theme configurations to be incompatible with the new Odoo version.

This can be fixed by

Checking the theme you are using

Locate the error

Add data type checks 

Clear cache and recompile assets

https://www.odoo.com/de_DE/forum/hilfe-1/odoo17-version-after-installation-styling-not-loading-238399

Check out my answer to this. It mybe has something to do with cashing - try if it' works in Chrome incognito mode.

And there was an issue with caching.

If I deleted the assets in the database they got regenerated and then it worked again.
res = env['ir.attachment'].search([('url', 'like', '/web/%')])

res.unlink()

I'm facing with same problem. 

In February I installed Ubuntu 24.04 server and Odoo 18. I created a test base and everything worked fine. I tested as a custom module. Now I updated the latest odoo core files and even a clean test base does not work. I get the message The style compilation failed. Ubuntu has the same libraries as in February. I removed Enterprise so the problem is in Odoo core.