That seems like an extreme amount of data for any 'password' app, unless it is some game that is played (a lot!).

Anyway, have you asked your son about it?

Can you find the app via:

Settings
Apps
Show all apps
(tap 3 dot icon)
Show system apps

?

If so, and you scroll to the bottom of the page, it should say something like 'Installed From...' and that will tell you where it came from.

If it says Play Store, then look it up.

If it is nothing needed, uninstall it.
If it is a system app, you won't be able to uninstall it, so you are safe in that way.

If it can be rid of, but your son still desires a password app, try Bitwarden.
It is simple, works great, and syncs with all your devices.

I does not use data unless you are using it, and then it uses very little.

https://bitwarden.en.uptodown.com/android

 

Ok, at this point, do the
Settings
Apps
Show all apps
(3 dot icon)
Show system apps

again.

Go all the way to the bottom of the list.

What you are looking for is an app with no name, and no icon, that is still taking up space like any other app.

This is generally how malware/adware hides on a device in my experience.

Because there is no icon or name, it won't show up in the app drawer, or by a search, or other ways either.

Sometimes normal seeming apps can download junk like this, and it can be anything from ads to phishing, or other crap.

Anyway, the good thing is that if you do see such junk, just delete all data from the app and then uninstall the app.