2015 Yukon XL rear AC blower has recently been stopping and starting working for no apparent reason. Have not noticed it cycling on and off while car is running, but it happens between engine shut off and restart (not working on way to work yesterday, working on the way home, and then not working again this morning). Anything other possibilities besides bad blower motor?

bad ground.
?

Set it to highest setting, if you can, before starting the vehicle and see if that makes it start each time. It's probably just the blower motor getting old and failing, they tend to be cheap but I'm not sure how hard a rear one is to get to.

The brushes could be getting wore out on the motor.