From my personal experience, project or bounty manager banning bounty campaign participants on their telegram channel or group is not necessarily an indicator that the project it self is a scam, there are many participants that like asking unnecessary questions and many even like breaking the rules of the group or channel, so when this kind of people are banned from the group, it does not mean the project or bounty is a scam, I have participated in a bounty campaign where I got banned in the group chat, but later got my payment and sold for some money