You can easily access any undeleted convo in any app if you achieve device access. I would like to read more about this to understand it more and because your reply is still a little unprecise, do you have links to examples?
I've no proof of this, but technically the whatsapp app is closed source so they could push an update that collects the private keys, if they don't do this already
One way to prevent this is would be to re-sign the app with your own signing key and delete that key before court, I guess. But those people whose conversations appeared probably just had Google Drive plaintext backups enabled.
What events point there?
There were several (ex) Meta employees stating they could read any message if they wanted to.
Source for this
A number of WhatsApp conversations unexpectedly appearing in courts.
You can easily access any undeleted convo in any app if you achieve device access. I would like to read more about this to understand it more and because your reply is still a little unprecise, do you have links to examples?
I've no proof of this, but technically the whatsapp app is closed source so they could push an update that collects the private keys, if they don't do this already
One way to prevent this is would be to re-sign the app with your own signing key and delete that key before court, I guess. But those people whose conversations appeared probably just had Google Drive plaintext backups enabled.
I don't know about WhatsApp, but macOS backups your keys on iCloud by default, so...