The dollar hasn’t had a stable value for years as it is a fiat currency, and as such is a political tool.
Comparing the dollar to an overinflated commodity means nothing. Gold hit a bubble price and the bubble popped, as did real-estate in the US.
Comparing the dollar to a real market basket of products that is the same year after year, is representative of normal buying habits, and isn’t cherry-picked to skew the results does mean something. In this comparison, you can see the dollar has lost nearly 90% of its purchasing power since the 60s, an is still headed down. There are minor blips here and there, but the decline is very predictable.