Hello @corsaunelec;
It is not just the category pages. Your homepage is also experiencing the issue.
It is because of this error:
Refused to apply style from '<URL>' because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled.
Your server is not loading all of the css stylesheet. Please ask further assistance with your hosting provider and ask them “Why all of this css files were not loaded.”
Meanwhile, 2 3rd party plugin maybe causing this. You could try testing for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
Please let us know how it goes.