I have a laptop and monitor that I hook up with an hdmi cable, I always would run nvidia mode because it would boost performance for the monitor. Laptop is a 1920x1080 @ 144hz and my monitor is a 1920x1080 @ 144.01 (according to xrandr). I would have my monitor either at my left or right side as I had to change my desk around, Both of which worked fine. I would use my monitor as my primary display. I was on Plasma and would go out and use my laptop as a laptop without my monitor, every time I connected my monitor I would reboot to refresh the Plasma session and do the same every time I disconnected it. It was working just fine until at one point it just stopped. I hadn’t changed any cables, any settings, nothing. It was most likely an update that broke it, but I have no idea which one, if any.