When a string is passed to a boolean evaluation, the empty string '' returns False. Any non-empty string returns True. So "not string" is True if the string is non-empty, False if empty.

Which language?

Please use a spoiler flag when posting code in a comment (I set the flag for you this time).

But i written this code in VSC on my PC and here was nothing wrong
So what's the difference?

Try calling your function a few times with cases from the sample test case. I just tried your code, and Nope! it is only able to pass few test cases before exceeding CW's Time Out limit

But i written this code in VSC on my PC and here was nothing wrong
So what's the difference?

Most probably you did not test your code with inputs which cannot be handled by your solution. You tested it only with inputs which work.

it definitely is possible, i just submitted my code
edit: and i regretted not refactoring my code before submitting

Your code is incorrect. You're going into an infinite loop. Read here to get some ideas about how to sort that out.

And with a total amount of submissions going soon to be 10k, how interesting that nobody never noticed that the kata does not work, uh?