Asked the same thing a few days ago - for text, it's apparently a bit pattern embedded in the choice of synonyms (there's a "red" and a "green" set of words, and the sequence of "colours" forms a signature). But that obviously doesn't work for code... Maybe it falls back on some UTF8 shenanigans with zero-width joiners or something?
https://mastodon.social/@phoerious/117082910882164401