Interface looks broken after update, which about:config to blame?

Describe the problem you’re having:

See screenshot. The interface looks broken in my firefox. I disabled all add-ons and it didn’t help, but starting with a fresh profile fixed the ugly artifacts. I have quite a long list of about:config changes made by me and add-ons.
Have anyone else had this issue and figured out what was wrong?
I tried disabling resist fingerprinting and other low hanging fruit, but no luck.
20

tt-rss version (including git commit id):

latest commit: 7a98105960dcbb53b4a221e2337ac7d1c955bd92

Platform (i.e. Linux distro, PHP, PostgreSQL, etc) versions:

FF on MacOS

i’m gonna blame your inability to search before posting

https://discourse.tt-rss.org/t/drop-down-menus-have-text-not-arrows/1703