Water inside rear compartment in 428i convertible

[cjdispatch]

I took my 2016 428i in for an oil service the mechanic told me I have water sloshing around in the rear of my car. Anyone else experience this. You can hear it when you put on the brakes.

[328 Power 04]

https://www.bimmerforums.com/forum/showthread.php?2319937-Location-of-frame-drain-hole-for-4-series-convertible-F33