I personally wouldn't mess with added fatigue as the normal rules only apply fatigue if characters miss sleep anyway, so I don't see why this scenario would be any different. It was probably the writer not realizing exhaustion is not a PF2e mechanic.
Also does anyone know what the "business hours" of the bank actually are and what time the characters start their planning. It says that they have 12 hours till the bank reopens in the morning, but it also states that it is assumed that the characters rob it during the daytime...
