[tskj]

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.

[esafak]

So when you cause an incident because you did not pay attention and "learn your lesson" who's the mentor?

[tskj]

The universe.

Anyway, I accept this usage of the word "lesson", so I also accept "learnings". My point was one of hypocrisy, not policing people in how they can use the word "lesson".