MongoDB atlas containers not separating from testcontainers

we are moving to mongodb atlas and I've started using the mongodb/mongodb-atlas-local container for local development, it bound to ports 27017:27017. Now I wanted to update our integration tests to use the new container but I have some strange behaviour. This is my old code that worked, there is some extra code so it starts as a replica set so I can test functions that use transactions

@pytest.fixture(autouse=True, scope="session")def init_mongo_get_uri():    mongo_container = DockerContainer("mongo:latest")    mongo_bind_port = randint(a=30000, b=40000)    mongo_container.with_name("python_testing_mongodb")    mongo_container.with_exposed_ports(mongo_bind_port)    mongo_container.with_bind_ports(container=mongo_bind_port, host=mongo_bind_port)    mongo_container.with_command(f"--port={mongo_bind_port} --replSet=rs")    mongo_container.start()    # normally the stuff above would be enough but we need to start the container with replica set to be able to test functions that use transactions    # starting with replica set takes a second so we need to wait for the container to be ready    mongo_uri = f"mongodb://localhost:{mongo_bind_port}/?replicaSet=rs"    max_attempts = 10    for attempt in range(max_attempts):        exit_code, output = mongo_container.exec("mongosh --quiet --eval=\"rs.initiate({_id:'rs',members:[{_id:0,host:'localhost:%s'}]})\" mongodb://localhost:%s" % (                mongo_bind_port, mongo_bind_port)        )        if exit_code == 0:            # If the command succeeds, break the loop            break        else:            # Wait for 1 second before retrying            sleep(1)        if attempt == max_attempts - 1:            # If we reach the last attempt and still fail, raise an error            raise RuntimeError("Replica set didn't get setup properly after 10 seconds")    yield mongo_uri    mongo_container.stop()@pytest.fixture(scope="session")def test_app(init_mongo_get_uri):    # Additional check to ensure the MongoDB container URI is not None    if not init_mongo_get_uri:        raise RuntimeError("MongoDB Testcontainer URI is None in test_app fixture.")    # Setup the MongoDBSingleton with the container URI    MongoDBSingleton._instance = None    MongoDBSingleton(uri=init_mongo_get_uri, db_name="testdb")    #start flask app

Now the mongodb/mongodb-atlas-local image uses replicasets by default so supposedly no need for all that extra stuff.

@pytest.fixture(autouse=True, scope="session")def init_mongo_get_uri():    mongo_container = DockerContainer("mongodb/mongodb-atlas-local")    mongo_bind_port = randint(a=30000, b=40000)    mongo_container.with_name("python_testing_mongodb")    mongo_container.with_bind_ports(container=27017, host=mongo_bind_port)    mongo_container.start()    mongo_uri = f"mongodb://localhost:{mongo_bind_port}"    yield mongo_uri    mongo_container.stop()@pytest.fixture(scope="session")def test_app(init_mongo_get_uri):# same as before

Here my knowledge of either Mongo or docker or both are failing me because even if the new integration tests run against the testcontainer on a different host port I still see the testdb appear inside my local dev 27017:27017 container, and if I stop the tests with debug I can use compass to connect to the testcontainer on say port 37017 and I'll see my local databases there as well.

I have tried binding the atlas testcontainer to something other than 27017 but it seems that isn't allowed.

What am I missing so I can run the testcontainer without it "polluting" my dev-container? I would have thought that having different host ports would be enough.

EDITIt seems when my local dev db is turned off I can't access the test one at all unless i run it on 27017:27017.