IPV6 address – Dead Beef!!!

Hello,

I downloaded NextDNS which is a DNS.firewall service. whilst trying to get NextDNS to work with my WIFI, noticed in my windows 10 WIFI settings the following IPV6 address for NextDNS – fd42:dead:beef::/64. A little message from my hacker friend(s) I believe. My question is what can I assume from this with regards to the safety of my laptop? How would anyone be able to add such IPV6 address?