This happens right after wake up:

enter image description here

What is the problem? Nvidia or Ubuntu?

And where to report this bug? Can't find Nvidia proprietary drivers repo on Github.

By the way it's nice to see Nvidia dirvers' logs:

Fixed a bug that caused system hangs when resuming from suspend with some GPUs.
Fixed a regression that could cause corruption when hot-plugging displays.
Fixed a regression that prevented systems with multiple DisplayPort monitors from resuming correctly from suspend.