"Kk," for those who are unaware of every tiny internet argument...
At its core, it's an acknowledgment that a message has been received.
The Internet® credits online gamers with inventing "kk."
This message board comment explains that it was used because it takes less time to type "kk" than "ok." And every split second counts when you're playing online.
This Quora response on the origin of kk dates it to "circa 1996," and this "Net for Beginners" breakdown of the term gently reminds you that "90% of the time, these expressions are typed in all lowercase letters. On selective occasions, you are welcome to use them in all capitals to express enthusiasm. Just remember not to type entire sentences in all caps, lest you be considered rude."
So don't "KK" someone. OK? Kk.
I mean, "OK" is fine.
And, yes. I'm fully aware this isn't a popular opinion.
I mean, sure, "kk" isn't something to be bandied about all the time.
And some people are genuinely confused by it.
But, come on. You can't just stop at "K."
And what if you've already said "OK"?
If you think I'm overthinking this, then...
But think about it.
So the way we communicate with one another matters.
And that includes the subtleties, quirks, and regional flair that occur in mostly text-based communication.