What would constitute sufficient proof of a spiritual realm for you?

This has been on my mind a lot. In my opinion, science itself isn't advanced enough yet to either prove or disprove the existence of metaphysical phenomena, and it may never be. A "spiritual" experience in and of itself wouldn't count as proof necessarily either. Personal experiences are biased and can easily be debunked with psychological screenings for disorders or just by the mere understanding that sometimes, by our human nature, we experience what we subconsciously want to experience. We are biased.

In my opinion, in order to have real proof, one would not only have to have a personal experience, but that experience would have to be paired with a reception of some kind of knowledge that would have otherwise been unknown to that person. Maybe that knowledge would include knowing what someone in another country is doing at a given moment despite your not being there physically, like with astral projection. Or maybe it could describe receiving detailed prophesies in advance that are made known to other people beforehand and, once the events predicted occur, are verified with those people to eliminate bias.

My definition of proof in terms of the spiritual is very specific, but to me it's a lot more logically sound than someone who "just knows" that their beliefs are true, if that makes sense