At a bank you get your deposit back.
If you store USD in a bank account your returned deposit will have less purchasing power than your initial deposit thanks to inflation. If you get less purchasing power back from your bank, I don't think that really counts as getting your deposit back.
I think it does count as getting your deposit back. Any time you put in a deposit and get it back it has most likely
lost value due to deflation. You're pointing out the obvious.
I don't think you know what deflation means. The USD deposit will have lost value (purchasing power) due to USD
inflation, an increase in the USD money supply. This is one of the problems that Bitcoin has the potential to fix.