Magic Mouse is only right-clicking
I found this issue from a while back:
Why is my Magic Mouse only right-clicking… - Apple Community
I'm seeing the same behavior.
For the last few weeks my Apple Magic Mouse (white) has been misbehaving. It won't right click sometimes/at all; then, if I disconnect/reconnect it will without error, for a short period. Basically just intermittent issues. I'd gone through the same troubleshooting steps as in the post; nothing really worked.
In this case I just happened to have another Apple Magic Mouse (black). I plugged it in and all the goofiness went away. So, it could be that...
When the Apple Magic Mouse fails, it doesn't just flop over, dead; apparently it could just be obnoxious until you retire it. I'm sure it was at least years old so I got my use out of it but GOOD LAWD, what a pita.
I hope this helps the next person.