I believe this section of our documentation covers why you are not seeing Cloud Storage reduced.
"Before we remove cloud data, we check that no snapshots still reference that data. This process is called garbage collection and is a background service running on the device. Removal of cloud data is not immediate as the garbage collection service checks for other references to that data before the deletion. The speed of garbage collection depends on the total number of snapshots and the total data. Typically, the cloud data is cleaned up in less than a week."
Hopefully this answers your questions. If not please let us know and happy to look into this further for you.
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