Three seeds were hidden on the page, and a bonus puzzle on Twitter.
Open the block details on creeper and look around to find 64 hexadecimal characters.
In reality, it wasn't supposed to be so easy, hence a bonus puzzle on Twitter containing a question as ban_ address:
WHAT BASE ENCODES A BAN_ADDRESS?
Note: The bonus puzzle was the one intended. So, what happened? The block I sent leaked the address in the "Link". Oh well.