Image on plane reversed (or something) in render

I’ve been away from Blender for a long time so … well, I’ve forgotten a LOT! :o

Anyway, I have a scene set up that uses a plane with an image texture as a backdrop.

When I set rendered mode in the camera viewport the image is displayed. However, when I actually render to an image, the image is reversed (maybe?) or otherwise no longer the way it appeared in the viewport.

I tried applying (and resetting) scale/rotation, and tried resetting the uv unwrap and then unwrapping again.

Nothing seems to fix it. It’s a part of an image, so I can’t even really tell in what way it is messed up.

Thanks for any suggestions!