I switched from Proton to Mullvad and I would highly recommend switching in that direction, not vice versa. Proton was unreliable for me for starters. And Mullvad requires no personal info—not even an email address—and you can pay in cash. Mullvad "just works" for me, whereas I had connectivity issues with Proton semi-regularly. You may also have more privacy/political concerns with Proton e.g. them handing over a French climate activist to the police, or some people take issue with the CEO's comments on Trump. Mullvad has no such incidents like the former, and I'm not aware of Mullvad involving itself in politics beyond privacy politics.

But for piracy specifically, you may want port forwarding. I've heard AirVPN recommended for that reason, so if you're looking to switch, you might want to look into that instead of Mullvad.