It’s about picking up treasures. Sometimes the treasures are near a tree, even a single tree, and it just makes it annoying to try to pick it up because the tree wants to be selected. Yes, this is probably just a campaign problem and not even a big issue I guess. But I’m sure the same thing will happen with relics also.
Have you tried to rotate camera? maybe resolve your issue
Yes, rotating or zooming works. But maybe trees shouldn’t be a selectable thing while having military/ religious units selected.