Why is ethereum’s unlimited supply not a problem?

Genuine question. 18M ETH get created annually for each year forever as far as I'm aware. Is this 18M at least hardcoded? I think it's at least better than fiat if it's hard coded and steady and not subject to human manipulation. But if this number is not hardcoded, I just don't see how it's any difference than fiat in terms of over exerted monetary supply ultimately devaluing the currency. Also please forgive my lack of knowledge on ETH especially if this info is easily available. I guess I just saw the unlimited supply and got a bit concerned.

Edit: I took this 18M number from a likely dated article. Thanks for the replies pointing to how this rate of issuance has shifted with EIP-1559.