Basically I am using mull on android and librewolf on linux.I want to use firefox sync or something line that for syncing.So how good Firefox sync is, in privacy point on view. I am not anonymity paranoid I just want privacy so basically what do they collect and for what?
You can find a detailed description about Firefox Sync’s design in regards to privacy here: https://hacks.mozilla.org/2018/11/firefox-sync-privacy/