Bug or Feature: Going to earlier levels after to 5-star later on spawns later game diseases

I have not checked whether this happens during the actual story replay, since to get a late 5-star on a prior mission you go right into the sandbox mode that comes afterwards.

It requires immediate and total redesign of that hospital for all the new diseases, stripping it of its identity; the mission it came from.

For starting a sandbox with later game mechanics unlocked already, an option for starting it "as level" or "with everything" would be nice. That could then also fit at the end of replaying the story, as to whether you want to allow all the later stuff in to switch to that mode.