The job of preventing scammers from the group cannot and should not be left in the hands of bots alone in my opinion, there has to be an active presence of a human agent closely monitoring the group even with the bot active. Bots alone will not be effective against some scammers.
A bot isn't used to stop scammers in most cases, but bots are used to prevent users from spamming the group and sending links because you can't send links in official chats of projects. It's against the rules, and you will get banned for doing that, and bots are set for such tasks. What a human operator or moderator can do is ban people who are present in the group and are trying to scam people by sending them DMs and impersonating to be either admins or project members.
Telegram is mostly known for impersonation scams because scammers over there are pretty good at copying others, especially when they get into an official group where they can find admins and project members, and whenever a member asks a question or tries to look for help, these scammers reach through DMs and start behaving like they are there to help the user from the team and then they scam them.