WordPress+bluehost…CSS not loading on admin panel

WP version: 5.7.3

I’m maintaining a WP server with hosting on bluehost, we update the site periodically via custom plugin and theme updates, last release was a week ago and everything went fine, site is still running OK.
Two days ago, an issue started happening when I enter admin credentials to dashboard of WP administration, there are no css styles and an error shows up on console, the error is the following:
Failed to load resource: net::ERR_INCOMPLETE_CHUNKED_ENCODING
Sometimes WP admin site loads correctly, but I think it has to do only about cache, because the majority of functions doesn’t work, for example, when trying to upload a plugin the nginx page for HTML error code 500 shows up.
I contacted support of bluehost but they couldn’t do anything about it.
Since is a bluehost hosted server, I can’t really modify configurations file of WP, and I don’t think the custom plugin and theme are the problem because they were working ok until two days ago (they are working ok, whole site is working, problem is when I try to enter administration panel).
I would really appreciate any help, or if anyone has had the issue and knows a fix, thank you!!!