Cannot control cursor, Mac OS Big Sur on late 2014 iMac 27"

I was able to get this sorted out today, by disconnecting and reconnecting USB devices. Oddly, one USB 3.0 hub, through which I had successfully been doing my TimeMachine backups for quite some time (as well as occasionally connecting something else), appeared to be the offender. I eliminated it and added a different USB 3.0 hub and rearranged what was connected via hub versus direct to the iMac, and it seems all is well now. My cursor is free as a bird again, no matter what pointing device I choose to use. Which is a relief, because I was beginning to wonder if 1 or 2 USB ports on the iMac were failing. But, not time for a M3 iMac just yet, not today anyway!

Thanks for your support and maybe our conversation will help other folks with older Macs who might see stuck unresponsive cursors all of a sudden. Always the best reason to "Ask the Community" is to help others besides ourselves.

Thanks for the screen shot! Yes, there were 2 AC powered hubs in the mix. Now only 1. I believe now that adding the second one damaged the first one.

Thanks, BDAqua... this didn't really work for me, almost no change in the behavior afterwards, but I am going to research Reset PRAM further to see if there are other details or caveats posted elsewhere that I need to consider, like disconnecting USB devices or something like that.

Thanks.