I use ProtonVPN with Ubuntu 23.10 and it works fine. I also use it with Windows and the only difference I’ve noticed between the two is that port forwarding is a lot more fiddly to setup in the Linux client, whereas it just works out-of-the-box with the Windows client. For that reason, if you’re doing a lot of torrenting you may wish to look at alternatives, though as I understand ProtonVPN is one or the few remaining good VPNs with port forwarding.