Ok, here's my experience with my new M1 Mac Mini and Bluetooth issues.
Chapter 1.
My MM came with Big Sur after upgrading from my 12 yo iMac. The old-girl is still performing but slowing because of increased software size and digital certificates. Migrated everything from my iMac to the MM using Time Machine backup without a problem. On initial boot only the new mouse spectre came up but not the new keyboard so I couldn't enter anything. Used my old magic keyboard and got through everything ok to be up-and-running. I read several blogs on the same problems. One suggested using a wired usb keyboard, which I couldn't get my hands on. Another suggested turning on the keyboard accessibility function in settings, which I did. Connected my new bt keyboard ok and everything was good. Noticed delay in key entries and sometimes lagging (have since found out that there are now time-outs on bluetooth devices, some not all). So that explained lag with initial keying. Have to hit any key and wait a second or two for the keyboard spectre to tell me its connected.
Chapter 2
Had a power failure from storm while using the MM. On power-up again would not connect my new keyboard or new mouse this time. Also, the screen accessibility keyboard didn't appear. My old magic keyboard wouldn't connect either. Spent time on phone with Apple support trying to explain everything. I sensed from the person I was speaking with that this wasn't the first time they have had to deal with this problem. They were willing to repair the MM if I could get it to an Apple store, this would be in Sydney or Melbourne. I live 6 hours away from Sydney and 4 hours away from Melbourne. Long story short...... after 2 weeks they sent an authorised technician from Wangaratta. He brought with him a new bt antenna and a brand new motherboard. He wasn't very forthcoming with information but I sensed that this was a hardware problem.
Chapter 3
I of course had to go through all of the initial setup again but this time the keyboard and mouse spectres both appeared telling me that they were connected. I've been using my new MM system for 3 weeks now with no issues although whatever keyboard I use there is still sometimes minor key lags and key repeats from normal typing. I observed that sometimes one of the letters that I typed didn't appear in the word I was typing but did appear in the middle of the next word I typed. So what I'm saying is that bt or the MM is messing up the sequence of send/receive. I'm now running Monterey and will be pursuing the keyboard issues.
