MongoClient should raise an error when given multiple URIs. Currently the behavior is to parse all the URIs and combine all the hosts which doesn't make sense. A single MongoClient can only connect to a single cluster, passing multiple cluster URIs like this should raise an error:

MongoClient(host=[
    "mongodb+srv://cluster-a.abc12.mongodb.net",
    "mongodb+srv://cluster-b.abc12.mongodb.net",
    "mongodb+srv://cluster-c.abc12.mongodb.net"])