I get that too, it can be difficult to get help. I try to ignore it and have been using Linux for about 15 years as an OS. I use Kubuntu on my laptop, but I’ve used Mint also. I’m thinking of changing back but it’s so much work, and there are a lot of other options I’d like to try.
I’ve had my network locked out as well, the first iteration of ProtonVPN I used would lock it out if you didn’t close the app before shutting down. I contacted Proton and they sent me the commands to unlock it, so I have them handy in a file. That problem was fixed, afaik, because I can shut down without exiting the app now. I haven’t had my comp suspend, Linux used to have a problem with suspend so I’ve stayed away from it. I haven’t had any problems with Proton otherwise, I used it on my Android as well, I have a paid plan.
I use it on my Linux laptop, there’s no port forwarding, dowloading works fine though, sometimes connects to peers to upload. I have dual boot so I have seen the Windows version, it’s much more sophisticated. I’ve checked for DNS leaks using one of the sites listed in another comment, no leaks.