"shrinkflation" was a term which tried top capture the size instead of price. But if you want to stay within the price semantics, then your good old deflation, stagflation, inflation will do just fine.
I think when the op said "cheaper" they meant the quality of the product is lowered, not that the price is lowered (I also thought this is what they meant at first and was very confused)
Yeah you're right. I stuck to the old askreddit rule of not adding clarifying text and put it in my comment instead. That kind of gets buried though. My bad.