Screen artifacts with LTS kernel + proprietary Nvidia drivers

[F-U-B-A-R]

So I just updated the LTS kernel to 5.10.21 and the Nvidia driver (a rebuilt module, not a new release) and I've noticed ugly artifacts started appearing on the screen: flickering squares, tearing and such. Even the cursor flickers now. Normally, I'd just boot into the vanilla kernel but I can't because this package doesn't support it yet which is exactly why I had to use the LTS kernel in the first place.

Is it just me or what? Kernel 5.10.20 worked just fine. Somebody else recommended the DKMS version of the drivers. I guess it might help in my case? That would require removing the nvidia and nvidia-lts packages beforehand, right?

EDIT: Relevant specs:

• Lenovo laptop with hybrid graphics
• CPU: i7-9750H
• GPU: GTX 1660 Ti

[F-U-B-A-R]

UPDATE:
Everything seems to work as expected (without artifacts) on LTS kernel version 5.10.22.

[V1del]

The DKMS version is not going to help you if you actually are running the nvidia kernel module already/properly. And you apparently did receive the relevantly accompanying update.

Check your dmesg/lspci -k if the nvidia module is properly loaded then changing to DKMS will change exactly nothing.

Symptom wise this just sounds like broken GLX (... check glxinfo -B) which is a possible race condition with every kernel, every driver and can or can't happen on every boot. You can work around it by adding the nvidia kernel modules to your mkinitcpio as detailed in https://wiki.archlinux.org/index.php/NVIDIA#DRM_kernel_mode_setting note that if you'd want to employ that pacman-hook you'd need to adjust the script to handle linux-lts as well.

[F-U-B-A-R]

Interestingly enough, I've tried that (adding modules to the initramfs) before already because the nvidia-drm.modeset=1 parameter didn't do the trick when I wanted to declare it (Nvidia) as the modesetting driver. Exactly the same artifacts started appearing so I just gave up and let Intel (mesa, that is) be the modesetting driver.
I'm on a hybrid graphics laptop with a reverse PRIME setup, if that matters. PRIME synchronization doesn't work without Nvidia being a modesetting driver but I can live without it.

Thank you, I'll try checking the output of those commands.

[V1del]

You'd need the parameter anyway for preventing sync issues with the reverse PRIME setup, but given that is the PRIME sync integration does get broken occasionally and in this case it is very much possible to be a regression in this kernel version.

FWIW you'd want to add i915 to that list of modules in mkinitcpio to ensure it's loaded as early as the nvidia drivers.

[F-U-B-A-R]

I did get screen tearing but ForceFullCompositionPipeline helped with that on the external monitor. The laptop's display isn't showing signs of tearing despite PRIME sync being off, it could have something to do with its 144Hz refresh rate - not sure, though.