Does instagram notify when you screenshot a story - what's the real answer?

same goes for screen recording, nothing for stories. the bit that does catch people is vanish mode in DMs, screenshot in there and the other person gets a notice in the chat. and ignore any app that claims it can tell you who screenshotted your story. there's no data for it to read, those are just after your login.

No. Stories, posts, reels — none of them notify. The one exception is disappearing photos and videos sent in a DM, the view-once sort. Screenshot one of those and the sender does get told.