"Warning: Display 1: No cameras rendering" when all cameras render to RenderTexture

I have a setup where all cameras render to RenderTextures and I display those textures in the appropriate part of the UI with RawImage. However, I get the warning “Warning: Display 1: No cameras rendering”.

Is a camera which is not rendering to RenderTexture really required? Can’t I have all my cameras simply set up to render to RenderTextures?

I’m rather new to Unity myself, but my understanding is you have to have at least 1 main camera.

What you could do is have a quad display the RenderTexture, and have a simple, orthographic main camera set to look at it, both somewhere out of the way of the rest of the scene, and with the quad positioned so as to cover the correct part of the total image.