/check link: tells you whether a link is on a known threat list. It works everywhere, also in DMs, and never stores the link. Moderators see a Why? button with the matched entry and its sources. Paste an invite (a discord.gg link or a code) into the same option and it resolves the invite and tells you whether it leads to a reviewed scam server; it never reveals whether Defendr is in that server.
Example
/check link:hxxps://evil[.]example/login