But you still have to pay the fiat equivalent in bitcoin to buy stuff? So you'll have to pay more bitcoin in year x+1 as compared to year x 🤔
Simply because more and more fiat is created, meaning more fiat is available over time, relative to things available to purchase.
Bitcoin is deflationary, because less and less Bitcoin is available over time relative to things available to purchase.
Fiat Currency = Stuff/∞ = 0 Value.
Bitcoin = Stuff/21,000,000 = ∞ Value.
As nostr:npub1ck7pm46mpx49rjaqpc93xlc7u8668fnze4un9zjwkvvsrn84820srlqqwqsaid, "Bitcoin has nonstop, because Fiat has no bottom."
Discussion
But you're right, bitcoin will become dearer in fiat terms
Almost everything gets cheaper on a Bitcoin standard. The cost of products and services generally goes down as systems become more efficient over time.
Most people are just used to things becoming more expensive as the currency is gradually debased.

True, efficiency should bring down prices
I think that's what Lyn Alden talks about in her book Broken Money