Ubuntu 18.04 diaplay is wonky after trying to set the resolution

I tried this: Ubuntu 18.04 Displays Issue -> Unknown Display

Namely:

ubuntu-drivers devices

sudo ubuntu-drivers autoinstall

because Ubuntu stopped recognizing my Acer second monitor and now it looks stretched.
Also, this: https://superuser.com/questions/679923/ubuntus-max-resolution-is-1024×768-unknown-monitor

Namely:

xrandr --newmode $(cvt 1280 1024 60 | grep Mode | sed -e 's/.*"/1280x1024/')

and now I’m getting some weird temporary blackout and noisy pattern on the background which I can reset manually.

Here are screencasts showing the problem: https://drive.google.com/drive/folders/1AbFhuxQD7yS-p_S4iFEJAxNkrKusM8_a?usp=sharing

Does anyone have any suggestions on how to fix this?
If I can get it to recognize my Acer second monitor too, that’s even better.