Omg, even the thing that is enshittifying everything is now being enshittified itself.

In my experience, a Scheduler is something that schedules time on the CPU for processes (threads).

So 10 processes (threads) say “I need to do something”:
2 of those threads are “ready to continue” because they were previously waiting on some Disk IO (and responsibly released thread control while data was fetched).
1 of the threads says “this is critical for GPU operations”.
1 of those threads self declares it is elevated priority.

The scheduler decides which of those threads actually gets time on an available CPU core to be processed.