If people in the chat want him suspended, I guess it is those people with the complaint making a recording/listing of the chats and then passing the evidence onto authorities.
Someone in the group chat is a snitch.
I thought only 1-to-1 messages were encrypted and group chat wasn't.
Whatsapp does E2E for groups, which have upto 256 members. A Matrix dev said they scaled E2E to groups with thousands.
The group chat is also encrypted, but anyone in the group chat can share the messages.