Backups are not encrypted by default. It just takes a single person on the other side of the chat not enabling e2e for your messages to be readable.
Meta data is also not encrypted. Your messaging graph is known to Whatsapp including message timestamps.
Also, IIRC, they (Meta) could also partially bypass the e2e (they can't access past messages but they can receive future messages) without you noticing (unless you have certain settings on whatsapp enabled, settings most people don't even know they exist).
The new feature of sharing past messages with new arrivals to a group also further widens the potential scope of messages leaking.
alt Hacker News
Backups are not encrypted by default. It just takes a single person on the other side of the chat not enabling e2e for your messages to be readable.
Meta data is also not encrypted. Your messaging graph is known to Whatsapp including message timestamps.
Also, IIRC, they (Meta) could also partially bypass the e2e (they can't access past messages but they can receive future messages) without you noticing (unless you have certain settings on whatsapp enabled, settings most people don't even know they exist).
The new feature of sharing past messages with new arrivals to a group also further widens the potential scope of messages leaking.