Idea:
Put barrier blocks on the tree that hiders can reach, but hunters can’t.
hiders-can-get-onto-an-inaccessible-tree
More information:
I’ve seen players hiding on those trees myself and didn’t even realize it was an out-of-bounds spot at first. The tree isn’t visually outside the map, so people can get there accidentally, if a leaves-block hider boosts them up by hiding next to that tree. Adding just one barrier block would fully prevent it and would stop constant reports about players hiding there.