have you checked the fluid level and see if there are any leaks or abnormal amounts of fluid missing? Could be a number of things, air in the system, maybe the lines to the accumulators were not tightened all the way causing a small leak & air to enter? Did the shop also touch the leveling valve by chance?

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2001 E55

2001 E320 Sedan

2001 Subaru Legacy

2006 SLK280

2016 Subaru Outback 3.6