For those who don't know (including me) could you explain what you mean by deprecating BTRFS? I don't understand how the file system is relevant to a file syncing app like Dropbox.
Neither does.. well anyone. Dropbox decided to drop support for BTRFS and pretty much any other Linux file system that isn't ext4, and to my knowledge still hasn't explained their rationale to this day.
Sharing the reason is either a legal risk, or a loss of competitive advantage risk (some optimization that only works when their whole pool is in particular format).
As of last November, Dropbox only supports ext4 on Linux, NFTS on Windows, and HFS+/APFS on Mac. Couldn't tell you the technical reasons for the change, but they're listed here:
