I believe I bumped into a unintentional "turbo mode" for the "V" key. For what I've tested, a tool assigned to it only remains active for as long as the button remains pressed. Upon releasing it, the previously selected tool becomes active. Though a nice functionality to use with some tools such as the move tool and the eraser, it is so specific and I haven't found it to be described anywhere.
That's probably because V normally temporarily switches on the line tool when using the freehand brush tool.
Make sure you disable V + click in the canvas input settings.