Take a look at the file where the ripple behavior is defined: .venv/Lib/site-packages/kivy/uix/behaviors/touchripple.py
I would recommend copying this file, giving it a new name in your local project directory. Rename the Behaviors(ie MovingTouchRipple) in the file and modify the code so the ripple effect moves with the base widget class. The pos of the base widget class
here will be self.pos.
Just taking a quick look - it is not obvious what to change. There are a number of methods that handle the drawing and animation. You will need to figure these out, so the animations move with the button widget.