In timeseries $out we clone the indexes of the collection and we always work in raw/physical format. This is achieved by only targeting either (the buckets NS without rawData) OR (the main NS with rawData:true).

However while retrieving the indexes we check AllBinariesSupportRawDataOperations feature flag with two different FCV snapshots (here and here), so there is a race condition where we may target (the main NS without rawData) under a concurrent FCV downgrade. This will retrieve the indexes in logical format, which is unexpected.