Fuel pump impeller failure (recall)
The same defective fuel-pump impeller recall that hit the CBR600RR covers these bikes (NHTSA 24V864000 for 2008-2017 and 2021; 24V113000 for 2018-2019) — the impeller deforms and the pump dies, stalling the engine. The recalls are recent, so assume the work has not been done until proven otherwise. Check the VIN for an open recall and ask for the repair invoice.
Ask for repair records covering this item. If it hasn't been addressed and the car is in or near the mileage window, price the up to $550 repair into your offer — or make it the seller's problem.