Firefox password manager
Question regarding Primary Password protection. Since there is no sync going on between different devices for PP, what happens if someone hacks/gets access to my Firefox account password and then installs a brand new Firefox on another machine? If I understand correctly all of my passwords in the password manager will become available to the attacker since there will be no primary password protecting them on the new machine. Please correct me if I'm wrong.
Opaite Mbohovái (1)
The PP is specific to a device and each device has its own PP and this PP is only used locally and is never part of Sync. Sync uses its own encryption key to encrypt all data locally before it is uploaded to the Sync server. You need to make sure that your Sync password is strong enough that it can't be guessed and you need to to keep it safely like you always need to do with passwords. You can possibly enable 2FA on the Firefox account for more security.