Is it just the desktop or full screen games as well? Does enabling triple buffering in nvidia-settings help?

Where do you enable that exactly?

there is no triple buffering option in nvidia-settings!?
just generate a xorg.conf file:
nvidia-xconfig
and in the Screen section add:
Option "TripleBuffer" "1"

example:
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 24
EndSubSection
Option "TripleBuffer" "1"
EndSection

you can also remove ForceFullCompositionPipeline
works for me with kwin

My bad. I didn't remember you had to set it in xorg.conf. Sorry, should have checked. It's been a while since I needed that particular option.

Further info:

It seems the tearing only happens on my 4K screen and not my 1080p screen.

For Unity games I simply use KWin compositing, since I'm using KDE in general (not switching it off for fullscreen windows). It works very well to prevent tearing.

Triple buffering is enabled for me, but it doesn't help on its own.

Seems it's fine in Cinnamon, so I will stick with it.

triplebuffer option is bad when you want to record gameplay's. even with nvenc it kills perf on some games and quite a lot. + causes all sorts of weird framerate issues. Not Every game is affected by it though.

ForceCompositionPipline fixes everything for me.. but i have no idea about 4K resolution.. might be broken there?

I use Compton compositor. Tbh, I've not had screen tearing in a long time on XFCE with Compton, even in games I just disable vsync in games as the compositor handles it just fine.

My massive compton start command:
compton --vsync opengl-swc --paint-on-overlay --backend glx --glx-no-stencil -c

compton is all good but makes the windows move slower and takes a bit perf hit.
also recording will be pain with compton. there will be screen tearing on the video