This may be helpful if you haven't found it yet. It has a full list of instructions to flash and configure openwrt on the rpi 4 with wireguard VPN. It says you can also do it with openvpn, but claim the speed was much slower.

https://www.instructables.com/Highspeed-VPN-Router-With-Raspberry-Pi/

I don't use Fedora, but do you know if your kernel or GPU drivers have been updated to a newer version? If so, there could be some kind of bug causing it, and you could try downgrading your packages. I would also check to make sure the refresh rate on your monitor matches your OS. The Steam logs would also be a good place to start, if you haven't checked them yet.