UPDATE

mongodb@3.6.5 is out.

Just update mongodb driver and mongoose:

npm i mongodb mongoose

This is caused by the mongodb@3.6.4 native driver which is used by mongoose.

#1 You can downgrade mongodb to version 3.6.3 (described here).

#2 Or downgrade mongoose from 5.11.16 back to 5.11.15:

npm uninstall mongoose
npm install mongoose@5.11.15

#3 Or just wait for the release of mongodb@3.6.5.

For all those looking for an answer for this, there is a question posted on Mongodb forum and the answer is acknowledged by Mongodb concerned person.

The answer given by @kmgt is correct. The error can be ignored safely and will be fixed in upcoming release of Mongodb Nodejs driver or downgrading Mongoose version to 5.11.15 will help.

(node:44612) DeprecationWarning: Listening to events on the Db class has been deprecated and will be removed in the next major version

Same Error

But As far as I know its a new version compatibility bug, after searching about this current bug version, I found this comment session and according to one of them, it is safe to ignore this warning.