They posted an article a while ago with a high level overview of how FF Sync encryption works, but the TL;DR is that the key for E2EE is derived from your accou

They posted an article a while ago with a high level overview of how FF Sync encryption works, but the TL;DR is that the key for E2EE is derived from your account password. https://hacks.mozilla.org/2018/11/firefox-sync-privacy/ https://hacks.mozilla.org/2018/11/firefox-sync-privacy/