Firefox is usable with some tweaks and not that evil, even though sponsored by Google. But many people feel that they can't believe Firefox like 10 years ago.
Some users feel it's so wrong that they have forked the project: LibreWolf, which seems a good option too.
Not entirely true. The mullvad browser adds a lot of anti-tracking stuff, which was originally implemented in the TOR Browser. So you're definitely safer using the mullvad browser instead of plain Firefox