i gave up on firefox when i couldn't stop it from connecting to Google on a network device i was working on. Removing all the links from the advanced settings made it fail to start. That's when I realized how hypocritical they are. ( arm64 firefox-esr.) Even the latest chromium on arm64 connects to Google almost daily. i use epiphany-browser for that project now. no unwanted internet traffic from epiphany.
Yeah when my DNS went sporty I noticed Firefox got very slow to load even local ips and investigated.
Turns out it does two dozen queries on every start. Mostly to unknown Mozilla services but also a few from Google and others I couldn't identify (IP on either AWS or CloudFlare, likely just more Mozilla). And when it can't resolve those hosts it seems to continually retry every few seconds...
Before the apologists arrive, try it yourself. Disable all your add-ons and set your homepage to blank, close Firefox, start wireshark, start Firefox and watch the avalanche.
