As a native (Commonwaelth) english speaker of six decades+ .. it only really "appeared" in frequency during the past decade, more heavily in the past five years or so, in central north American settings.

Grammerly will tell us:

  Despite being more popular than “lessons” in the corporate setting, “learnings” is still incorrect. It's an erroneous plural form of the colloquial term “learning.”

As a business-speak buzz-word it might fade, or it may end up with a greater global footprint outside of the Biz-speak Babel tower.

Probably due to the movie "Borat! Cultural Learnings of America for Make Benefit Glorious Nation of Kazakhstan".

People missed the joke that it was poor English on purpose.