>>10904943it's believed to be this setting. the filter is extremely defective and just randomly bans entire accounts across all channels that have the setting enabled.
this setting is designed to be used with live moderation, to manually allow or deny the messages after review. however, cover does not provide such live moderation, and in practice the messages from affected accounts are never reviewed. the behavior of youtube's chat software is terribly inappropriate because it does not present an error message to channel members when it's blocked by this filter, but cover is also using the setting inappropriately by failing to provide any review of held messages.
