I tried Rider 2025.2 and 2025.3 both with jbr 21.0.6-b895.109 and 21.0.8-b1148.57. With the former there are no problems, but with the latter a basic mouse pointer is shown instead of the system one and pop ups (context menus, tool-tips, floating windows) are placed partially outside the screen boundaries.
I use NixOs GNU/Linux (tried with both 25.05 and 25.11) with i3 wm (x11).
Reading the logs in ~/.cache/JetBrains/Rider2025.*/log/idea.log I couldn't find nothing relevant.