[theamk]

No, that post says the file is "marked with special metadata" - it does not say that is is only metadata.

So my theory is that Google Drive file = full chat log + metadata. The only server where the chat log is stored is Google Drive one. Deleting Google Drive file deletes the chat log. Recovering Google Drive file recovers the chat log. Not recovering Google Drive file means it's eventually purged. The link thing means that chat can be accessed even when it's in the trash can.

Have you went to Google Drive and checked the sizes of those files? If they are the links, they should all be the same. If they are raw data, they should be smaller for older files and bigger for newer files. Please check and report.

Also, download the file and open it in editor. Does it has your messages, or does it only has a pointer?