This has suddenly happened to me also, on the mac in my signature. I've had sreensaver set to ten minutes, and display sleep set to one hour. Computer is set to never sleep. I've had it like this for many years, over many versions of macOS, and many different Intel/ARM mac models.
Suddenly it's not working. Screensaver just runs and runs. I have not changed anything lately; not macOS v., not installed or upgraded any software, all connected peripherals are the same.
Did you find any solution to this?