There is nothing about a "vault" in the terms of service or fee disclosure list. What are you talking about?
<a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/4129819-getting-to-know-the-turbo-prepaid-visa-card">https://ttlc.intuit.com/questions/4129819-getting-to-know-the-turbo-prepaid-visa-card</a>
<a rel="nofollow" target="_blank" href="https://www.turboprepaidcard.com/legal-info#cardholder-agreement">https://www.turboprepaidcard.com/legal-info#cardholder-agreement</a>
<a rel="nofollow" target="_blank" href="https://www.turboprepaidcard.com">https://www.turboprepaidcard.com</a>
In my app for the card, there's an option that says stash... And it takes you to something called a vault where you are supposedly able to put money back.
There are no extra fees. (It looks like the "vault" is just a way to hide money from yourself so you don't spend it.)
Okay that's what I need to be sure of. I know there's fees for Green Dot in general. I don't want to stash money and then it all goes to monthly maintenance fees over time.
The card itself has pretty significant fees, $4.95 per month unless you make $1000 of deposits or more each month. Having money in the vault does not by itself incur fees but if you put money in the vault and then set the card aside and don't use it, you will indeed get nibbled to death by ducks. And it doesn't earn interest (although it's hard to find even 1% interest on deposits these days.)