Hi Dan.
I am aware of some clunkiness with the new game settings interface with respect to some interaction with the interface for each player to interact with their personal panel of options.
However, it is not my expectation that using the mouse to change the level of play while a player is associated with a joystick would have any impact on the joystick player, unless perhaps the joystick's selection focus had been moved to the game level of play and then the mouse took focus of that option afterwards. I at least had anticipated preventing the mouse from doing this--but quite possibly I forgot to address it. Alternatively, perhaps it should just redirect the joystick (or keyboard) selection focus back to a default entry in the respective player's personal panel of options.
If I have not accurately described what you are seeing, I would love to see a video or receive additional details. Two places come to mind for submitting video:
Support Email:
mailto:muleonlinehelp@gmail.com
Discord:
https://discord.gg/eSMCJ2NGdQ
Thanks!