iCloud iCloud Drive and Facebook Messenger Questions

[IhaveaniPhone]

Facebook says this:

"Restore Facebook end-to-end encrypted messages with iCloud Drive"​

Does this mean that it's possible for deleted Facebook messages to be recovered through iCloud Drive as long as they were encrypted? Or if I delete a message on my phone is it also deleted on iCloud Drive? And would the messages restored on iCloud Drive be any different than the ones I Facebook will let me download on my computer through the "secure storage" option?

Or is the information stored just login information, encryption keys, etc.?

 

[Sweet_Caroline]

This is to transfer from an old device to a new one.