GitLab Enterprise Edition 13.3.1 Page Rendering Issues

[jwq]

My workplace has just upgraded our self-hosted GitLab Enterprise Edition instance to 13.3.1-ee and I'm seeing multiple problems with Seamonkey 2.5.3 fetching and rendering page content:

• on the Project Overview page, the Last commit and Last update columns are not populated.
• Issues report error banners "Something went wrong while fetching comments. Please try again." and " Failed to load related branches"
• Merge Requests report error banners "Something went wrong on our end. Please try again!"
• pages intermittently stall while loading, showing an incomplete page body.
• the Error Console shows large numbers of errors on the css file <https://gitlab.../assets/application-30 ... 27828f.css>

These problems occur on two different installs and are reproducible in a fresh default profile. Firefox 72 threw a similarly large number of css errors but Firefox 79 and 80 render the pages without error.

Edited to add: Even a single entry from the error console output is too large to post here due to the inclusion of the source css which is 227000 characters. The output on the console is:

• Warning: Error in parsing value for 'font'. Declaration dropped.
• Warning: Unknown property 'zoom'. Declaration dropped.
• Warning: Expected declaration but found '*'. Skipped to next declaration.
• Warning: Unknown property 'user-select'. Declaration dropped.
• Warning: Error in parsing value for 'background-image'. Declaration dropped.
• Warning: Expected 'none', URL, or filter function but found 'progid'. Error in parsing value for 'filter'. Declaration dropped.

and from this point the warnings repeat.

[Frank Lion]

These problems occur on two different installs and are reproducible in a fresh default profile. Firefox 72 threw a similarly large number of css errors but Firefox 79 and 80 render the pages without error..

Perhaps just use Firefox 79 or 80 on that one edge case website?