Learnings implies a report of your own experience; lessons implies something prepared as teaching material for the audience. (In the context of the title sentence anyway.)
‘Lessons’ to me also seems to carry a sense of regret, as in ‘things (we) got wrong’. ‘Learnings’ is a more obscure word that I would take to mean something more neutral: literally ‘things (I’ve) learnt’.
Beyond what's noted there (contemporary business jargon), English is diffused across the globe and has many regional variations that are different than class-signalling/formal American and British usage. As we all encounter each other online, it's not always worth over-analyzing word choice when you can understand the intent.
Some words in Shakespeare have different meanings today or have simply left standard usage. I don't think the presence of a word in Shakespeare means it is de facto good style to use today.
From a correctness stand-point, I think a descriptionist would be satisfied with an attested usage, especially from such a source. From a style point of view, I still find myself feeling embarrassed for the author when I encounter this usage (which is my own problem).
I think when you ask what the difference between two phrases is, people will really dig down to try and find a difference.
IMO in this context it is basically shorthand for “things I learned/lessons learned while tuning LLM…,” and either would be fine. It is sort of an informal list of stuff the author learned.
In my experience (nothing special, just another native speaker) “lessons from <event>” is the more typical American (at least) English phrase. But it is sort of close to “Lessons on.” “Lessons on” would imply more refined material that is more narrowly focused on teaching. So I wonder if the author decided they just didn’t want to worry about any confusion, or the possibility that they might misuse a phrase.
Gotta earn those fat management consultant fees somehow. I’m sure there’s a whole team at McKinsey doing nothing but inventing new ways to say the same things.
In Swedish, there's a commonly used word "lärdomar" which is a direct match for "learnings".
But where the Swedish word sounds natural in that language, "learnings" just sounds wrong in English, even though it apparently is technically correct.