My Dell XPS 13 started to screen flicker / glitch after a software update (probably due to me adding some incorrect drivers, so I stated by removing those dependencies). It would often persist after restarts. The glitch was especially bad if I resumed using the laptop after closing the lid.

This issue was solved by disabling the Dynamic Backlight Control setting in the laptop BIOS.

Still have to avoid locking the screen with the superkey+L.

I had previously tried editing GRUB (using "quiet splash i915.enable_psr=0"), but it did not help in my case.