Interesting. I ditched team green years ago and have been running rock solid since. My Nvidia GPU was always the reason I went back to windows. Sorry to hear your ryzen rig stopped, have you looked for a bios update? Might be something simple like that (assuming your disk didn't shit the bed).
Can't say I've had any rdp issues on Bazzite, what's it doing?
That is definitely odd behavior. Multiple sessions is a server side setting, so your Linux system shouldn't be able to do that without windows being ok with it. As for the resolution issue, it might be a config issue in your client. Give another client a shot, or see if there's a way to configure the client to use smart sizing. I can't recall which app I use on my system, but I can't say I've ever had an issue with scaling between connected and remote connected sessions.