Comment # 1 on bug 1225065 from Richard Brown

> Is there any way to fix this?

You can go to the top right hand corner of the Installer screen and click the
tray there, choose the cog icon for Settings > Displays, and change the
orientation of the panel

I don't think wayland/GNOME can interpret nor honour the Kernel mode video=
parameter

Is this a satisfactory answer for you?