F11 suspension drop

[P700DEE]

I have a 2012 F11 520D SE with the self leveling rear suspension and I've had it 18 months now. I have noticed that after about 24 hours the suspension on the rear drops completely and only pumps up again when you start the car. It never used to do this. Is this a warning that the self leveling system needs attention , is leaking ? thanks

[IroningMan]

Airbags develop holes. They don't have to be expensive to replace if you use an indy specialist, and not a challenging DIY, either.