I don't call it normal,i name it scam. Close down bounty group means they don't want anybody to speak, blocked access to the spreadsheet means they probably don't want to pay the reward to the bounty hunter, what an ironic project.
Exactly, that's a matter of fact, if they are closing the bounty group and also blocked access to the spreadsheet means it is crystal clear that it is a scam and they have not had the intentions to deliver the reward to the participants. Now hunters get used to with such scams.