I have Lightning set to show the mini-month over the list of tasks and events instead of just the date. I have noticed that if my mouse passes over the mini-month shortly after scrolling in another Thunderbird pane, the month will abruptly scroll back or forth, too. It will even do that with the smaller date view, but is harder to do. I think this most commonly happens after scrolling and then going to minimize Thunderbird.
This is with Windows 10, Logitech mouse and drivers, and the latest Tbird, although I have really noticed it recently after I changed to the monthly calendar view. It basically sounds as if the mouse scroll message is not clearing once the mouse leaves a window pane. Not sure if it's a TBird or Windows issue. It can happen after using the elevator scrolls, or the mouse scroll wheel.
The pic below just shows the view I'm talking about. You set it with the "View/Today Pane >" menu entry.
