Pairing iPhone 12 to my 2015 MacBook Air

I have a 2015 MacBook Air, and had my iPhone 11 bluetooth paired with it and my Apple Watch was also paired to my iPhone 11 and my MacBook Air. All was good, When I opened my MackBook, the Watch would unlock my computer.

Then I upgraded my phone to an iPhone 13, and now cannot connect my phone via Bluetooth, I get a message "Connection Unsuccessful" "Admin's MacBook Air (2) is not supported. When I paired I got the code number and everything looks good, when I touch on the MacBook on my phones Bluetooth, I get the Connection Unsuccessful message.

Why would I be getting this message and how can I correct this problem?