Fractal calls them Historical rooms and they are rooms that I left on other apps.
I thought that when you leave a room on e.g. Element it’ll send a deletion request to the server and then to other servers if applicable. But I can see all historical rooms and the data is still there. It even shows when I left the room.
How scary is that?
Last event I saw in those rooms was that I left.
There were rooms older than a year :/