App sleeping is not a guarantee, your app must not send any outbound traffic for 10 minutes, if it's not sleeping, then it's sending outbound traffic.

Only I use the app, there are times when I don't use it all day, but the ram consumption in the database and the backend remains the same, how can I lower this consumption?

You may be the only one using it, but your site is publically accessible for anyone or anything to cause it to send outbound traffic.

What kind of app is this?

If I am accessing through the public network, it is a backend made in Java and consumed from a mobile app, I must configure it through a private network to avoid this consumption?

It needs to be public for the mobile app to be able to access it.

configure the private database and the public backend to be able to access it, but it still does not go to sleep, what else can I check?

no comprendo de donde proviene este trafico de la base de datos, si no estoy consumiendo ningun servicio

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