I've always assumed that undo history is ephemeral in any application I use, other than maybe an application where history is first-class in a timeline like Fusion360. I'm surprised to hear that people rely on it being persistent.
The feature's name has "persistent" in it.
For example applying the recover file (well it's a huge pitfall in vim on its own) resets not only the current undo history but also the "persistent" one.