Unknown server

I calmly entered Minecraft, when suddenly I saw a strange server in the network game. The strangest thing is that I don't have such a server in my server list + server version 1.21...., and I have 1.20.4. The server was only for 1 player and for a newer version, so I couldn't enter. The Internet was home (if suddenly a theory about public Internet arises)
(the fact that the version installed is higher, I don’t know how to install another one in the report)