Yes, it has lost value over that time, but in a relatively stable and predictable way
People's savings are getting robbed in a stable, and predictable way. I know. The problem is that to "opt-out" of this robbing, you need to play it investor. You can't just buy a gold coin, and sleep easy that it'll worth the same in 20 years.
and very slowly
Supply of money expands by around 7% per year, on average. That's not slow.