It think it should return nothing: no "z", no substring before "z"
in 2022, i found similar issue
bugged version
corrected version
(The new block if you want it)
I don't think that's a bug. That's actually intended to become like this, as it is the opposite of the substring of [] after [] block. Not a bug.
Yeah, we did it that way on purpose. I can see an argument either way, but our idea was "take characters from this string but stop when you get to a z."