Hey,
I own an LG Gram laptop (14Z90Q, Intel i5-1240p, no dGPU, 16GB RAM), and I installed Manjaro on it. Over X11 or Wayland, after a few hours of usage, the graphics driver crashes indefinitely until I reset the laptop. This manifests as a screen freeze, and if I alt+tab, I can see the usual window picker screen, and KWin notifications stating that it reset due to a graphical issue. These notifications keep popping up, and if I let go of alt+tab, the screen freezes again. I’m a moderate linux user, so I have no clue where to find logs for this kind of crash, but I’ll give them as you ask! I switched the graphics driver from the default (I’m pretty sure it was video-linux) to video-modesetting, and it keeps exhibiting the same behavior. Thank you for your help! 
If it is a driver crash, it should be recorded in the journal, maybe this:
journalctl --priority=err --no-pager
or
journalctl --grep "i915" --no-pager
My thought:
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KDE has GPU intensive effects. Maybe disable it?
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Does this happen when your laptop is in idle? Possible that entering a deep power save state, C6 for example, could result in a freeze?