Air suspension Fault

I apologise if this has been answered elsewhere but I'm after confirmation of a fault, with no information specific reader.

The obvious "suspension fault" warning comes on my l322 2006, but something happens I can't find anywhere.

The rear suspension will lower after an undetermined amount of time with audible click/clunk noises. Can be straight after parking or hours after.

This says to me it can't be a leak or the compressor? Intermittently the cabin will tell me it's too low but not all the time? It always resets on driving though.

Any advice or help is appreciated as I can't read suspension codes.

Thank you in advance

Leaking air spring(s) at the rear, do the soapy water spray test.
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