Why does someone keep offering me money to remove a jscalc app I made?

I made a sensitivity calculator for a video game and someone keeps adding me on discord, offering $1000 PayPal to remove it. The calculator isn't crazy popular or anything. They say it's for SEO.

Is this some weird black hat stuff? I don't want the money since there's a good chance it'll be sent from a hacked PayPal getting my PayPal in trouble. I'm just curious why they care so much.