In the Vault 7 leaks, Little Snitch was mentioned as something three letter people had problems with circumventing. I think it's worth considering whether this new attack surface is there by design:
I didn't follow up on the Reuters news piece from January titled "Exclusive: Apple dropped plan for encrypting backups after FBI complained - sources". Has it been confirmed? If yes, then your assertion is most probably correct.
That Reuter's piece is original reporting that Apple never responded to, so I would say that it's all but confirmed that they did in fact do this at the FBI's request.
https://blog.obdev.at/little-snitch-on-vault-7/