I toot had this issue on a Dell Latitude laptop (Debian Testing, Mate desktop). My custom mouse deceleration was the first issue i noticed missing, then the touchpad clicks were gone away, then i saw that the mouse/touchpad gui showed only mouse. I tried replicating the constant deceleration settings but the xinput options were very limited. So i removed the libinput diver and that was it.
Why was this functional regression done?