Can anyone please be so kind and explain to me what it means that some public keys from this puzzle (like task 130 but not task 66 for example) have been found which makes kangaroo and keyhunt with bsgs mode possible?

I thought we know public addresses as they hold the reward and the task is to find the suitable public key from a reduced key range. So what does it mean that the public key for task 130 is known and is 03633cbe3ec02b9401c5effa144c5b4d22f87940259634858fc7e59b1c09937852? I literally don't understand this.

Thank you