Don't leave matrix room when leaving group in WA

[witchent]

I am using the bridge as a replacement for Whatsapp as much as possible. In Whatsapp, if you leave a group (or get kicked), you can still access all the history, whereas this is not possible with matrix. I just found out the hard way that it's not even possible to rejoin the room using the Admin API on synapse after I left a very important group in Whatsapp.

Thus, I am asking if it would be possible to at least have a config option to not leave matrix rooms when you are leaving the WA group.
We could instead just send a message stating "you left the room" and make the message permission level higher than the users permission, so it will mimic the behavior of Whatsapp by leaving the history intact, but not allow the user to send any more messages.

(I guess this applies also to at least the signal bridge, so I am not sure where to open the issue - Feel free to move it to the correct repo).