Steam Play Deltarune intermittent black screen after unfocusing

[mahesh]

I'm running Deltarune via Steam Play, and when I Alt+Tab of Super+Click out of it, the window becomes black. When I switch back, the blackness lingers momentarily, but sometimes it stays that way. The game still functions, and I even managed to win a battle and SAVE before restarting it, but this is very frustrating.

I have no clue to what's happening, and I'm open to almost any kind of diagnostics. Please help!