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?
Personally I like using discord much better. Telegram is kind of a messy platform and there's a whole lot of scammers flying in with random bs and messages that you just don't get on discord. It's also probably due to the fact that Discord provides some sort of decryption that I believe is thought to be strong than telegrams.