My firefox installation always run in English with all of its interface elements being in English. One of the recent updates introduced a weird behavior - some of the UI became Russian. I seem to have fixed/bypassed the issue last time it happened https://support.mozilla.org/en-US/questions/1415337 but nothing works this time. Most of my firefox is in English, but some elements such as tab titles in devtools, browser popups "do you want to leave this page", tooltips in this very text form where I'm typing right now - are in Russian for no apparent reason. I have another profile on this firefox installation and it's completely in English as intended. I tried to check for what changed in about:config, looking for "language" or "locale" string, and there's nothing that stands out. I've tried clearing startup cache, switching language back and forth, restarting firefox. Any suggestions?