The moment of passing appears to bring an expression of relief to the deceased. But what is going on in our minds?
www.bbc.com
" There is no evidence suggesting that painkillers such as morphine would prevent endorphins from being produced, however. Pain isn’t always an issue when people die. My own observations and discussions with colleagues suggest that if pain has not really been an issue for a person earlier, it is unusual for it to become a problem during the dying process. We don’t know why that is – it could be related to endorphins. Again, no research has yet been done on this."
https://www.healthline.com/health/pineal-gland-dmt#production
that's an unproven theory...
i looked it up so i didn't have to hear anyone getting scolded for laziness, nor anyone recriminate that they should do their own research...
both unproven, not enough research for a definitive answer, either way.