when you open a change stream the aggregation command affects the latencyStats.reads on the oplog but subsequent getMore commands increment latencyStats.reads on the collection being watched despite not actually reading from that collection.

the bug may or may not be here https://github.com/mongodb/mongo/blob/f17987ea0fc43ad4d3b34dedd39336f0faac734c/src/mongo/db/commands/query_cmd/getmore_cmd.cpp#L674 when we create an AutoStatsTracker for the command namespace and not the cursor's namespace