Group PM vanished

A group PM here that I moderate vanished sometime last week (perhaps about the same time as the bots hit/the paywall went up? but hard to say). Looks like all of us previously in the chat can no longer find it in our accounts. Is this something that can be looked into/recovered? (And has anyone else experienced this with their group chats?)

@Thomas Umstattd Jr. @Darlene N. Böcek