On the MacBook Pro 14" when connecting to RDP the desktop displayed cuts off about 20-30 pixels at top and bottom. The MacBook display is set to "Default for this Screen" btw This is a great app...
I get this also on a regular macOS screen with 'Menu Bar visible in Full Screen' turned on - the top of the remote session is cropped to the height of the menu bar, as if the remote session resized to my screen height before the window maximised and found its actual pixel height.