PC Controller: Dying with rumble/vibration can lock that vibration in until the app is closed.

How: Died while casting a max stage flameblast with a lot more fire spell nonsense in my screen in Demon Form (I practically casted all of the ones that are currently in the game). Copy my character Wyrmnut if needed for testing.

Unplugging/replugging the controller in did not clear the vibration command.
Returning to character select / main menu kept the vibration going.
Only way to stop it was to exit the application.

I have the same issue with mine. I'm on a pc with the game straight downloaded and use a usb slot for my controller. Happens usually after a boss for me as well.