[pxc]

Disabling mouse acceleration that way hasn't worked right since Catalina at least, maybe even since Mojave. You can test it with a high-resolution gaming mouse: slide it across your mousepad once as slowly as you can, and then flick it across once. There's still a difference in how far the cursor travels, even with SteelSeries ExactMouse.

The only tools I know of that actually work for this (if you comoletely disable speed/sensitivity controls as well as acceleration) are SteerMouse and CursorSense, which use some kind of driver hack: https://www.plentycom.jp/en/index.html