cannot change name for Magic Mouse, Try this

[andrelabbe]

you can try various method but the 'original' name always come back when you turn the mouse back on

 

[andrelabbe]

Hi

Here the solution. No need to reset or edit anything.

You might have noticed under Catalina latest you cannot rename a magicMouse (might work for other devices)
When you turn it off and reconnect it is back to the old name

1. Connect Device
2. Go to Bluetooth preference pane, right click on device, don’t click the menu, leave it open
3. Turn off device, the menu is still opened
4. Select "rename" in the still open dropdown menu
5. rename the device and close the pop up
6. Turn device back on and connect

Tried it and it work a charm