Copy user ID and add the @ before posting or copy the nPub (public key)

I've done this several times. I add https://damus.io followed by npub, it redirects to the application used. Like this https://damus.io/npub17xmqghckxjkzrkes0h586jtxz9ac8ue45kjjp80tl4lc5h89sffqqec6pp