Players can build on spawn from time to time. I do not know why
https://gist.github.com/anonymous/d66f6a231dcbceeb9fda09ab523ee002
https://i.imgur.com/OccYguQ.jpg

The ? symbol means undefined, which translates to false if the user isn't opped.

Well its pretty simple - don't run cracked versions of minecraft unless your willing to put up with mismatched/spoofed UUID's.