There are many things in roguelikes that you have to die to learn how they work, how to form a strategy around, etc, but having the difficulty inspection of the game itself straight up giving false information should never be something a player should have to learn. It is the kind of thing that brings everything down around it, because if the difficulty isn't accurate on this thing, how can a player trust the difficulty inspection to be accurate on others? If I don't know what the ACTUAL difficulty level of an encounter is, how could a player possibly know when they are in a position to actually take on that encounter without gambling that the levels aren't so high they can oneshot you immediately.
I know patrols are an odd duck because they're a moving encounter on the world map instead of an actual character, but I think the game would be better off giving NO information vs FALSE information. Having NO information clearly communicates to the player that it is in fact a total gamble on what you will find in there.