Is there a hotkey to switch between multiple displays during remote control?
Yes, this is possible. However, keep in mind that on the host, you fist have to select or click into a window with actual content to be able to switch between monitors. If you click the desktop on the host monitor or the header of the remote control window itself, then you won't be able to switch to another display.
To switch displays, hold down the left CTRL key + left Windows Key, and use the left and right arrow keys to cycle through the available displays. The "All Monitors" option is part of this cycle as well.