Once i noticed something of this nature, then i block the user straight forward without hesitation, because there is no need of wasting time in reading what they have to offer, giving them audience is one of the ways we have already surrendered ourselves to them for further penetration, because its not proper enough for us to accept or engage in a conversation with someone we don't know, how do they managed to get our telegram username to have sent the message at first place, you cant see me join a random group i don't know about and once i noticed such, i exit myself and block such.