I am having similar issues (and maybe a few extra) in Kubuntu with, I assume, KWin:
Ubuntu 18.04.5 LTS with KDE Plasma 5.12.9 (Qt 5.9.5)
I don’t tinker a lot with my system and I don’t know a lot about windows managers, so please let me know if there’s anything else I can do to provide relevant information. I am having issues similar to what’s described above, but not exactly the same. I didn’t know whether it would be better to start a new thread.
In my case, it’s not that the window partially redraws or looks disjointed, but rather, the entire window does not update.
Sometimes I type and I don’t see my text appear without a few seconds’ delay; other times, the text doesn’t appear until I move the window with my cursor or resize it. Restarting the application temporarily clears up this state, but eventually, after minimizing and maximizing from the task bar some number of times, it becomes unresponsive again.
The main thing that is persistent and different from what it described by jorsk is that when I restore the application from the taskbar by single-clicking on it, I’m not able to resize it, because there’s nothing drawn and no window chrome to resize. When I minimize the Obsidian window, I can’t get it back at all unless I right click on the task bar and manually click ‘Maximize’, although when I simply click on the task bar there is a strange animation as if something is being expanded, but it doesn’t actually draw the Obsidian window. I tried to take a video, but the task bar wasn’t included – all that’s happening is that I’m either single clicking on the task bar when it doesn’t expand, or right clicking when it opens the dialogue.
not updating_compressed.zip (3.2 MB)
At the end of this video, although I’m typing, it’s not updating anything.
EDITED: As of this morning, VS Code is doing the same thing. I suspect this problem is not specific to Obsidian.