yeah, its due to brute force. But its happens to all visitors of all accounts in a server. so i cant find out the root cause of this issue.Check your brute force manager, because if they get into the ip_blacklist of DA, it's DA's BFM which is putting them there.
I think I already answered that recently to you, could be mistaken.
2022-02-22 14:36:53 login authenticator failed for ([127.0.0.1]) [160.242.113.91]: 535 Incorrect authentication data (set_id=developers)