In case just restarting the game doesn't fix it and if you're willing to do a bit of surgery on the game files:
This could be an incompatibility between the old version of NW.js that comes with RPG Maker MV and a newer graphics stack on your system, since the former is effectively an old Chromium from 2018.
The good news is that it's not customised, so you can download the "NORMAL" version from nwjs.io and extract it over the matching files in the GROVE… folder to update.
That's largely a guess though. I'm mainly suggesting it because it fixed hardware acceleration for me on Linux, but the game was already rendering for me regardless, even if slowly.