I have tried 3 different bluetooth mice and a USB mice and they all seem to only have certain areas that work. I am attaching an image that shows roughly where mouse clicks are working on a landscape Pixel Tablet. This also seems to be the area where the mouse wheel will work. Outside this area, only touching the screen or using a stylus seems to work. I also have a Pixel 6a with GOS that has a similar left edge that doesn't work in portrait.
https://i.postimg.cc/BQfSjvLp/Screenshot-20231103-103801.png