MongoDB connections suddenly got increased after redeployment!

Mongodb connections suddenly got increased from less than 20 to 500.
I’ve decreased to around 100 by adding these fields to connection string,

<mongo_uri>?retryWrites=true&w=majority&maxIdleTimeMS=60000&connectTimeoutMS=150000&socketTimeoutMS=90000

So my question here is how increasing these configurations will impact my pricing?
@Jason_Tran