Apple Bluetooth keyboard not connecting on restart
I just upgraded to Big Sur from Catalina. Now when I restart my computer I can only type the first letter of my password and then the iMac does not appear to respond to the keyboard. My keyboard is a bluetooth keyboard, the one that came with my 2019 iMac, and works fine once the system is rebooted. The only work around is to plug in a wired keyboard to type in my password. How do I fix this?
iMac 27″, macOS 11.5