For anyone who happens upon this thread in the future, it looks like this is an issue caused by the newest NVidia drivers (V. 555.85, released 5/21/24.) Reverting to the second most recent update completely fixes the issue as far as I can see, and this explains why my older commit also had the issue when I’m sure it wasn’t there when it was compiled.
However, this is probably worst-case scenario for fixing it, as now I’m not sure how to proceed, since I can’t just tell players to revert their nvidia driver version. I’m rebuilding the lighting from the ground-up with static lights and building the light maps out, but this is a tedious and annoying process after having done the work to set up the stationary lights… I’ll reply here if I happen upon anything else that will fix it, and in the mean time I’d love to hear from anyone else that is having this issue since getting the newest nvidia drivers.