I watched your videos and I'm quite confident it's the HDMI cable causing all your problems. (blinking monitor can occasionally mess with the GPU causing other issues like blur / "double vision").
HDMI cables these days are a joke IMO. First thing I've been doing lately for everyone I know is replace their HDMI cable on their PC with Display Port cable version 1.4 or newer (depending on their monitor specs). I find with HDMI cables, even opening a Chrome browser, the monitor will often blink off and back on again for no reason at all. This has so far happened to my friend, my sister, 3 of my clients and myself. HDMI standards are just not good enough.
Also, screw the makers of HDMI for refusing to support Linux.