There's this mushroom Lanmaoa asiatica that causes people to hallucinate hundreds of tiny people running around interacting with the environment. Consistently, across cultures and regions. You eat this mushroom and you're pretty likely to have a very similar hallucination to everybody else who eats this mushroom. Now is there some objective reality of hidden little elves everywhere that only this mushroom unlocks? Or is it a specific physical trigger that when people go through it they have the same sort of experience.

You can have the same question about the near death experiences. Are they experiences of an objective reality somewhere or is it a common physical situation triggering similar experiences across people and cultures.