UbuntuMATE 20.04 laptop display snow or flickering after update to kernel 5.13.0-27

I cannot boot using kernel 5.13.0-27-generic which was updated (automatically) yesterday. It causes the screen to flash some black and white stripe pattern after the ubuntu mate logo appears momentarily.

If I attach an HDMI cable and an external monitor, I can use the external monitor, but not my laptop display. Someone else has experienced a similar problem recently, see: Flickering snow on Laptop Screen in Ubuntu 20.04 with 470 drivers.

I am using the NVIDIA driver metapackage nvidia-driver-470 (proprietary, tested):

apt show --installed nvidia-driver* | grep "Version"
Version: 470.86-0ubuntu0.20.04.2

And these are the two graphics chipsets in my laptop:

lspci | grep "VGA"
01:00.0 VGA compatible controller: NVIDIA Corporation TU106 [GeForce RTX 2060] (rev a1)
05:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Renoir (rev c5)

I can still boot my laptop but only using one of the older kernels that is still installed - currently:

uname -r

The other versions of the nvidia proprietary driver that are available via Software & Updates (460, 495) fail in the same fashion.

For now I've set my laptop to boot using whatever kernel I last selected by changing grub as per: https://askubuntu.com/a/1308903

Update: I think this is more likely to be an issue with amdgpu? Similar to a report here: Static noise on laptop screen after update.

Also not working on kernel 5.13.0-28-generic.

I have solved the problem by switching from the HWE kernel - which is the kernel currently provided for the LTR UbuntuMATE 20.04 - to the OEM kernel.

An introduction to the OEM kernel is given here: Kernel/OEMKernel - Ubuntu Wiki.

The issue appears in at least the 5.13.18 and 5.13.19 kernels recently used in the HWE package linux-generic-hwe-20.04. The most recently available OEM kernel on Canonical repositories for 20.04 is version 5.14.20, found in the package linux-oem-20.04d, therefore to switch to the newer kernel:

sudo apt install linux-oem-20.04d

That's it! This took care of the DKMS so, for example, the nvidia and v4l2loopback modules were automatically inserted.

This will not remove the HWE kernel so it is still possible to switch back. To remove the HWE kernel:

sudo apt remove linux-generic-hwe-20.04
sudo apt autoremove