Use Firefox or Safari, the more people use Chromium-based browsers the faster we get to the situation where Google completely owns the Internet (andtheyalmostdonow).
What about Mullvad? I've been considering it for a while, especially because I really like the idea of vpn+browser resulting in the exactly same fingerprint as most of the other user of the same VPN, but I'm kind of unsure because I haven't seen almost anyone talk about Mullvad yet, which may be a red flag.
Mullvad is trusted. They are pretty open with their policies, exist for a long time already, not involved in any privacy scandals (to my best knowledge), charge flat and fair fee without 60% sales and other dubious marketing practices. It is one of the better VPN providers, not in 5/9 eyes (they are in 14 eyes though), you can buy a subscription with crypto, which (assuming crypto was acquired anonymously too) is a good start for some privacy guarantees.
Pretty much every cyber security professional I know uses Mullvad in one way or another, usually as part of a more complex solution.
But all in all, please bear in mind that VPN is not some magic silver bullet to preserve your privacy and anonymity. With VPNs you basically shift your trust from your ISP to the VPN provider. That trust you put into the provider, it is still a requirement. Not to mention that a good chunk of tracking is happening on a lower level nowadays, so if you use Mullvad on Windows / any Apple device etc. do not expect to become untraceable :)