High number of connections and opcounters without anyone using the cluster

The screenshot shows a period of 0 users on an Atlas Cluster linked with a MongoDB Realm app. As you can see, the second shard shows ~3 commands and ~2 getmores per second with ~60 active connections, and the other two shards maintain the same amount of commands and active connections as the second one, even though they have 0 of any other type of operation. This behavior is constant, the command operation never gets to 0.

Is this considered normal behavior for a cluster linked with Realm?

Now, this second image shows a period when some users (less than 3) start using the cluster by a MongoDB Realm Sync .NET client. Should the getmore operation go to ~5.5 per second and stay there constantly? And should the active connections go from 47 to 70 with 3 users connecting?