Most content sections in view issue not visible on Waterfox Classic

Summary

today i worked normally with gitlab until now as i had a regession in the user interface with waterfox classic. currently it is not possible to view the comments and details for an issue (have not checked if other locations are also affected.

Steps to reproduce

• download waterfox classic 2021.06 (use "classic" not "latest") https://www.waterfox.net/download/
• go to any issue on gitlab.com for example: #333595 (closed)

What is the current bug behavior?

missing nearly all userinterface parts in a ticket (see screenshots)

Relevant logs and/or screenshots

chromium

waterfox classic

Output of checks

This bug happens on GitLab.com

/cc @IzzySoft are you still a waterfox classic user? can you confirm?