I haven't seen any Gamblig Platform who used Telegram for Promotions, most I know is that they use Discord.
Do you have any Idea why they don't have any Telegram Communities? and why does it seem they don't use this platform for their promotions?
I think that Telegram has a bad reputation, especially on this forum, for being a place for scams to take place. Its too easy for impersonators to steal from innocent and vulnerable people.