The impact brain chemistry has on all sorts of things is very poorly understood.
There's this device called a "God Helmet" which purports to induce religious experiences on demand through electromagnetic stimulation.
https://en.m.wikipedia.org/wiki/God_helmet
There are other experiments with infrasound which appear to induce ghost like hallucinations:
https://higgs.ph.ed.ac.uk/outreach/higgshalloween-2021/haunted-frequency
Could all the sensations of "a presence" or ghosts or spirits just be by-products of electromagnetic or auditory pollution? Possibly. Nobody wants to look into it because "well, clearly, spirits and such aren't real!"
It's a decided lack of curiosity. :(