Why can't the viewfinder of Canon R camera be used?

There is an option in the menu, you can choose to automatically switch, evf, screen. In the case of r5, there is another option, that is, only when the screen is turned on, the screen will be displayed without switching to evf.

The viewfinder is a part of a digital camera, which monitors the image through the eyepiece. Now the eyepiece viewfinder of digital camera has black-and-white viewfinder and color viewfinder.

But for professional digital cameras, they are all black and white viewfinders, because black and white viewfinders are more conducive to photographers to make correct compositions.