I am really interested in how this solution works. Could you perhaps explain it?

Slick

One-line solutions are practical most of the time but this one example where they aren't. Although its efficiency may have passed the tests, you have to stare at the code at least a minute in order to understand what is going on.

Wow. A little bit difficult to understand at first, but after a while you start realise the cleverness of this solution.

But the knight is checking the king in that position: https://ibb.co/ykv4HKs.

You did not do the same thing. Compare your code with this more carefully again.

Bruh. I did the same thing but the program said there was an error in some random tests.

Dang it! Why didn't I think of that earlier.

Ah, thanks. I think I found where my mistake is.

You can print any relevant values yourself. See https://docs.codewars.com/training/training-example#debugging-a-kata

In the exhaustive tests in Python it only says that "False should equal True" or "True should equal False" when encountering an error but it doesn't specify why. I've read the description 4 times already and the only thing it says is that the program checks if the string is a valid Chess960 starting position. Every other fixed test says that I have achieved the goal. I'm stuck.