It is not a Telegram-related problem but you can face it in this forum, the crisis is bad in Telegram because thousands of accounts can be created without checking any information "You do not even need to verify the phone officially (any free VOIP will work.)"
Also, if you do not adjust your Telegram settings, you will increase the problem either, these are the most important adjustments you should make -----> Things a Newbie needs to know on Telegram.

Be safe and ignore all ICO/IEO groups