Jet2 has issued a warning to passengers, with some reports suggesting they should arrive at the airport two to three hours early, while others indicate a longer timeframe of at least 12 hours. The alert appears to be related to potential disruptions, possibly due to a software issue affecting Airbus A320 planes or summer delays. The warning seems to be targeted at UK holidaymakers, particularly those traveling to Portugal, although the specifics of the alert and the affected flights are unclear.