I keep getting invited to private Telegram groups

Just wondering, how the hell new group can mass invite random users in Telegram.. Cheers!

They are using automated programs and problaby have your username somewhere in a list that automatically adds you to groups. They usually scrape the usernames from other groups, so if you are already in other groups, then thats the reason why you keep getting added to new groups. You can disable it in the settings so you can stop getting invited. I think its on "Privacy and Security" >>> "Groups & Channels" >>> "WHO CAN ADD ME" - And then change the settings from there.