Its a common rule / unspoken thing in most servers, TTT or no not to advertise or glorify other servers or communities, same gamemode or no, as a player may go check it out, enjoy it more than TTT/SGM, and leave, which reduces player base. As pacifist said, its a case by case basis. For example, if youre just talking about another community you enjoy, youre probably fine. But if youre being very..strong about it, like "hey come check this server out/ come join/ lets leave here for a bit to play here" or using advertisement binds , or your username is a blatant advertisement it could get you scolded, warned, kicked depending on severity and if you comply with a staff members orders or no.