Timeshift on ext4 shouldn’t ‘fail’ you, whether that’s on Fedora Linux or with any other standard system that supports it. It’s only when you start trying to apply Timeshift to BTRFS that the snags and issues start to happen.
I don’t think that there is anything inherently wrong or ‘flawed’ with prefixing BTRFS sub-volumes with an ‘@’ in itself. It certainly does indicate to the user that there’s something non-standard about a folder or section of their file system. But on the other hand, it can make things look all a bit extrapolated and disconnected to standard notation, so I personally prefer the Fedora Linux approach.
The systems are the systems that we have though, whatever the decisions of senior managers or steering committees.
The main point of what I was trying to say, is that it is not generally a good idea to try forcing two basically different systems into configurations that neither set of system developers are expecting to see. If one team is going in direction X and the other team in direction Y, then eventually, at some point, one of the sides will release code that breaks what you are trying to do …
We need to remember that Timeshift is maintained by Linux Mint. Their repo on Github explains the system’s limitations.
An interesting avenue might be spinning up a Mint Debian Edition as a BTRFS virtual machine and seeing how the Mint setup might apply to a standard Debian one, perhaps ?
But having several years of core ‘long term support’ on a desktop that will usually have extra non-updated software added to it over time is something that should also be taken into account …