Maintaining wireless Apple Magic Keyboard with Numeric keypad connection to 2014 iMac

Apple Magic Keyboard with Numeric Keypad (USA version purchased in 2020) is not recognized by my 2014 iMac approximately 3 times per month. I utilize the Magic Keyboard to log into the iMac, but after log in is complete the home screen appears and a Bluetooth Setup Assistant pops-up searching for a keyboard. The Bluetooth Setup Assistant will search for as long as you let it but never connects to the Magic Keyboard, which was already used to log into the iMac. At this point you cannot perform any functions (typing, deleting, enter, etc.) from the Magic Keyboard. Most of the time connecting the Magic Keyboard directly to the iMac will get it connected and satisfy the Bluetooth Setup Assistant. At that point the wire between the Magic Keyboard and iMac can be removed. The Magic Keyboard will function for another week or so before the Bluetooth Setup Assistant pop-up returns. The Magic Keyboard has been above 70% state of charge for all these incidents. The iMac was updated to Version 10.15.7 about 2 months ago. The Bluetooth Setup Assistant pop-up started after the software update, but I cannot say the software update is the specific cause for the Bluetooth Setup Assistant. The Magic Keyboard has not had any issues over the 3 years it has been in use. Any recommendations to keep the Magic Keyboard continuously connected would be appreciated. Thank you.