Screen flickers on multiple computers (20.10)

Not sure if this is limited to 20.10.
Two weeks ago I send in an HP Probook 430 G6 (Intel Core i5-8250) under warranty to repair its display. I thought there was a hardware issue, due to all the screen flickering.

Today, on my desktop, an Intel Core i3-9100 based system connected to a Lenovo p24h monitor via DP, I notice the same flickering. I did a clean install on this system a few days ago:

I had taken a video for HP Support but I seem to have deleted it. Anyways, it gets pretty bad. I did not have this issue before (20.04). Not sure where to start to debug an issue like this.

In all honesty, HP wanted me to perform some tasks in Windows, as they needed to verify the issue had nothing to do with outdated software or drivers or configuration. I have an external SSD with WinToUSB on it and used that. During all of that time on Windows, I did not experience the flickering… I just decided not to tell HP as I thought it must be hardware related and perhaps I was not spending enough time on Windows.

But this desktop pc I have used 2 full days since I reinstalled it and I notice the issue today.

What could possibly cause this to happen?

It might be related to this:

I’ve been having a very similar issue with the intel graphics. There is a fix coming up it seems. It works for some, but mine might be a different issue because I am still seeing the issue with that newer kernel.

There is a workaround you can try in the meantime to see if it helps…

I had similar start happening after I did a recent upgrade of Ubuntu 20.04, to the extent that I couldn’t even login. The login screen just switched between purple and black, with no user menu visible. The same applies in 20.10.

From other posts here, I found that creating /etc/X11/xorg.conf.d/20-intel-graphics.conf containing

Section "Device"
Identifier "Intel Graphics" 
Driver "Intel"
Option "TearFree" "true"
End Section

(I have an Intel 915 chipset – inxi -G says
Device-1: Intel Xeon E3-1200 v2/3rd Gen Core processor Graphics
driver: i915 v: kernel
Display: wayland server: X.Org 1.20.9 driver: i915
note: display driver n/a resolution: 1920x1080~60Hz
OpenGL: renderer: Mesa DRI Intel HD Graphics 4000 (IVB GT2)
v: 4.2 Mesa 20.2.6

That fixed the login screen visibility, but I still couldn’t login. From another post here I tried using the settings cog in the bottom-right of the screen to switch to “Ubuntu on Wayland” and now everything appears to be OK.

Hope this saves someone in a similar situation some time.