Low impact double glazed patio window maintenance.
Don’t think that just because uPVC bi fold doors are reasonable and are promoted as “low maintenance” that you can ignore them completely, the frames and door unit as a whole can last a long time, but you will need to keep them clean to expect the appearance to stay fresh.
Having said that, the upkeep of uPVC patio doors is not that much work to cope with, washing the windows & frames every month should do fine. You could also check the hinges to make sure they are also free from dirt & debris because long term damage could occur as a result of ignoring these ‘hidden’ mechanisms.
If you have invested money in making you home better, then it makes sense that you should also invest a little time in keeping the doors themselves in good shape too.