I’ve seen and heard a few different times recently that using Tor for logging into sites that know your true identity (like banking sites) defeats the purpose of the anonymity of Tor. How would that relate to Mullvad Browser? Would accessing those kinds of sites defeat the purpose of MB? Or is MB more geared toward blocking trackers and some anti-fingerprinting?
This depends what you are using Mullvad for.
Logging into a service means that specific service can correlate your Mullvad session to your login/ personal details.
Tor/Mullvad on a bank seems a bit pointless because all banks already know you, your legal address, name, etc…
But since all information is wiped between sessions. My bank sees will see me banking, but didn’t see me watching youtube on Mullvad in the previous session as I did not log into my bank before I hit reset.