Hello everybody !
I have an annoying problem that I just solve, so I post here the solution, maybe it can help someone else.
If you have Gnome 43 with two vertical monitors, one top and another one bottom, you may have the mouse stick to the bottom edge of the top window when you try to go from top screen to bottom screen. Very disturbing.
This is due to the following extensions : Dash to Dock (go to dashboard, search “extensions”).
Go to parameters, and unset “show on all screen”
Hope that help someone.