I found the easter egg but I'm not sure what exactly it does. At first I thought it's one iteration of conways game of life but that's not it.
Enlighten me!
When you enter in an amount of text that is not exactly 129 base64url characters, it takes out the non base64url characters, turns them into 0-7 numbers, and then 1-dimensionally stretches those until i get exactly 256 pixels- and lay those out along the hilbert curve.