N of one but my friend (who always saw the world as very black and white) killed herself not long after doing Ayahuasca. I’m pretty sure it contributed to her death, she became an extreme fantasist about judgement and god, not a formalised religion but a personified fantasy with crazed rules and vengeances. It was not good.
I'm sorry for your loss. I'm not a medical practitioner but it sounds like the experience triggered a psychotic "break" in your friend? It's a sad but real possibility with psychedelics that more people should be aware of.
Whereas in other groups a cascade effect sometimes happens and many people in such groups can experience mental health issues, and trauma.
There's that common call to examine "set and setting" but it's often a crap-shoot, due to the chaotic number of variables.