Update: I’m still having the problem, but it happens infrequently rather than all the time. (M1 Mac mini (2020) and the problem started with Tahoe.)
First thing was I reinstalled the OS, then I went into the startup menu and removed anything unnecessary, I removed anything display related like Flux, and I removed VirtualBox (just because a process was running and I don’t use it). Not sure how much any of these have to do with the issue, but my main goal was to remove any unnecessary background processes, especially if it affects the display.
My monitor wakes maybe 80% of the time now. When it doesn’t, I have to unplug my monitor from my Mac and plug it back in.
Prior to this, I chatted with Apple Support for a lengthy amount of time and they confirmed it was a software issue and that they would hopefully fix it.
So I definitely still need a fix, but the issue is less annoying than it used to be (but still pretty annoying and unlike any other experience I’ve had with Apple).