Log traces include service metadata to specify the origin of the trace, denoted as "r" for router and "s" for shard, for instance:

{"t":{"$date":"2023-08-08T08:56:43.638+00:00"},"s":"I","c":"COMMAND", "id":51803,"svc":"s","ctx":"conn6","msg":"Slow query","attr":{...}}

This new field should only be returned by a node part of a sharded cluster, not replica sets nor standalone.