Loading a save game in a single-player campaign or other scenario will result in a chunk of one's stamina disappearing. It is only mildly inconvenient with the new stamina system, given how fast it recovers. However, it also affects the "Legacy Fatigue Mod" found on the Steam Workshop. Fatigue in that mod recovers far more slowly, making this issue somewhat game-breaking. I have not tested this with any other fatigue/stamina related mods.

Multiple consecutive save-and-reloads (save-load-save-load-...) have a cumulative effect. This includes user saves, auto-saves, and even save-and-exit.