Pairing Apple Wireless Keyboard A1016 with MBP M1, 2020
Mac running OS 12.3.1 won't discover keyboard in Bluetooth
Mac running OS 12.3.1 won't discover keyboard in Bluetooth
Depending on the generation it could be between 11 & 19 years old.
https://en.wikipedia.org/wiki/Apple_Wireless_Keyboard
How old is it? Is it charged or are the batteries fresh?
A tad more detail would be helpful. My position is you need to get a more modern KB.
Pairing Apple Wireless Keyboard A1016 with MBP M1, 2020