Sorry to revive this thread, but I recently got a MacBook Air (M1, 2020 Big Sur 11.6.3), and have been experiencing the same problems with my MK270 wireless keyboard and mouse combo using the "nano" receiver. I tried the nano receiver connected to a Adam Elements CASA HUB A01 and an Orico A3H7 hub. Using the MK270 on an old MacBook Pro late 2011 model works perfectly.
I then connected the nano receiver to a USB A to USB C converter and connected it directly to the M1 Air, and everything is now working fine. In my case them, when the receiver is connected to a hub, it causes delays/lag