Bottom of screen jitter w/ Quadro M1000M GPU, Nvidia 470.63.01 driver on Ubuntu 20.04

Hi there, I wonder if anyone encountered a similar problem before and figured out a fix for it.

What’s happening is that I run Ubuntu 20.04 on a laptop computer w/ Quadro M1000M, and if I use the laptop’s monitor, there would be a horizontal band of jitter (around 24 rows of pixels on the bottom of the screen but the rest of the screen looks fine), which is very annoying, as shown in the animated gif below (the application opened is gedit, and the text editing area is OK but the bottom status bar is in the jitter area).

output

Interestingly, if I use an external monitor, this horizontal band of jitter doesn’t appear. If I use an external monitor + the laptop monitor and mirror the display (both monitors share the same resolution of 1920x1080), the jitter will still exist on the laptop monitor, but not on the external monitor. Whether the external monitor is connected to the laptop’s HDMI or thunderbolt or mini DP does not affect this observation.

I have also tried various versions of the Nvidia driver (e.g. v470, v460, v450) and the jitter would still be there. I also tried to switch the display manager from lightdm to gdm3, and it also doesn’t affect the band of jitter.

I am quite sure that it’s not a faulty laptop monitor. There’s no jitter in BIOS and the Grub menu. And if I uninstall the Nvidia driver, the jitter does not appear when Ubuntu 20.04 loads. Similarly, if I boot other OS (e.g. another version of Ubuntu from USB thumbdrive w/o the Nvidia driver), the jitter also does not appear.

Any thoughts?