MongoDB Connection Pool Proxy
Currently there is no Connection Pool proxy supported by MongoDB.
With the ever increasing use of serverless and containers, clusters will need to be over provisioned in order to account for the increased connection counts.
A better solution would be a Connection Pool proxy allowing for a many-to-one relation for connections to MongoDB.
In the case of Lambda, this would reduce the number of Zombie connections (Connections that have been terminated on the Lambda side but are still open on the server side.)