I tried this one just now, using only one of the most basic sudoku strategies, and I immediately passed
all tests. No guessing or backtracking is required. This kata should be rated kyu 5-6 imo.

lol Well I did not say all kata rated 3 should not be rated 3, I said that specific one sudoku should not be.
I give my opinion based on the fact, the gap between this kata and the one with rectangle rated 2 is quite big!
So either that one should not be rated 3 or the kata with rectangles should not be rated 2 or may be the gap between kata 3 and 2 is more than one would expect.
You tell me Mr 2 dan expert !?

and how would you know after solving only 2 whites aside of this one...? x)

I was working on that https://www.codewars.com/kata/5a8f42da5084d7dca2000255/train/javascript but got stuck.
So got advised to solve a couple of sudoko before, I've found this one quite easy to solve and I would not rate it as 3.

thanks for your quick response, it's more than enough, I'm gonna keep working on it. Thanks

Could you please check my question and give me a hint. Thanks