A pluralization once popular in 14th Century Middle English that died out until ressurected in central north American business English.

In 2016 Grammarist was to the point.

    "Learnings is a pluralization of an erroneous form of learning as a singular noun. Said singular noun (e.g., a learning) does not exist, at least according to most dictionaries. Colloquially, especially in the medical field, learnings means specific items that were newly discovered or learned."

https://www.quora.com/What-is-the-plural-form-of-learning-Is...

they're since softened that stance and now discuss how it is poorly used.

https://grammarist.com/usage/learnings/

The word invented/resurrected, for some reason, to replace the word "lessons".

Exactly.