Is there are way to block not cache downloader?

not cache downloader means who dosent allowed to download cache files from server(set in multiplayer option)

this makes people can’t see MOTD so they won’t see rules.

anyway to detect and kick them?

AFAIK if someone doesn’t download the LUA cache file, as in they make it so they don’t download anything, nothing works at all on their end. So, if they didn’t download the cache file, they wouldn’t be able to do much anyway.