Learnings is irritating to me. The way kids use the word aesthetic is irritating too. I wonder if I might be that old man shaking his fist at the clouds, but I have gotten over begs the question, and literally, so maybe not yet...

I understand the instinct, but that's a bit too prescriptive for me.

https://en.wiktionary.org/wiki/learnings

A lesson would be a specific learning activity happening at a specific place and time, administered by a person more knowledgeable than you; like a teacher or mentor "giving a lesson".

If you're fine with the generalized form "learned a lesson", then surely "learnings" is fine too. There's no point in trying to police a completely normal and sensible use of language.