I’ve been mulling this over for a bit now and I feel compelled to argue that Mora is a fiat currency of sorts. A fiat currency is minted at will and is not backed by any commodity price. Being able to use Mora to perform alchemy is not the same as being able to trade one Mora for a set amount of a commodity. There’s also no real evidence that the value of Mora is determined by its alchemical exchange rate. Thus, we must surmise the value of Mora is determined some other way. It is also unrealistic to assume the Qixing is able to set commodity prices across the continent, meaning there are no Soviet style price controls to determine the value of the currency. The lack of any other meaningful currency in circulation (even in Natlan, where it makes absolutely no sense for there to be a centralized currency let alone for it to be Mora), means the value of Mora cannot be determined via comparison to other like stores of value. Since the value of Mora is not determined by a commodity or service price, it is not determined by price controls, and it is not determined by exchange rates, the value must be determined by the supply of Mora in the economy. The more Mora there are, the less valuable it is and vice versa.
The purpose of a central bank is to regulate the amount of currency in circulation. However, under a modern monetary theory framework, the central bank is only half the picture. The other half is the fiscal policy of the state. Currency enters the economy through debt. Governments create currency by borrowing money to spend on public services. Crucially, the money spent by governments always comes from debt, not taxes. The government is spending money before taxes are even collected. They simply add some numbers to a spread sheet and then sell that many more bonds. And again — this is crucial — the money is appropriated before any of the bonds are issued. Governments are simply powerful enough to make things happen and the accounting is taken care of afterwards. Taxation removes currency from circulation, using it to pay down the debts accrued in financing the spending. So you can begin to see the finical alchemy at play. Debt creates currency either through fractional reserve lending by private banks or through the issuance of government bonds to finance spending. In setting interest rates, the central bank can regulate the “price” of debt, which determines how much tax the government needs to collect to pay down the debt it has already used to finance spending. Banks purchase this government debt and use it to back their loans, which sets off the cascade of fractional reserve lending which then further creates currency from nothing. But that is always downstream of government spending and government debt. Thus, spending and taxation form two sides of a balance which determines the value of the currency. Spend more, tax less, the value of the currency is diluted as more of it enters the system than leaves. Taxes more, spend less, the value increases as the amount of currency in circulation decreases. At no point does the currency refer to any commodity, service, price, or other currency. Its value is backed by the purchasing power of the state.
(Modern Monetary Theory is a truly beautiful thing to behold <3)
To understand how Mora could be a fiat currency, we can analyze it through this modern monetary theory framework. Most obviously, the alchemical consumption of Mora is akin to taxation because it takes more out of the economy. Once upon a time, Morax minted Mora which the Qixing then spent. Thus, until recently, the Qixing was functionally the US government to the Mora’s USD: its spending determined the supply of a universally accepted currency. Now, we have to assume that the traveller’s leyline harvests fill the role of Morax and her spending the role of the Qixing. This paints a grim picture: as my original post suggests, a financial crisis is coming as the taxation of Mora (alchemy) is going to far outstrip the spending of one immortal teenager. But the system, in theory, holds. Mora is a fiat currency and its value is determined by spending and taxation. How long crisis can be averted depends on how much Mora is currently in circulation and how easily the Qixing can exploit Lumine.
Ultimately, Mora is now doomed to become BitCoin, a commodity that LARPs as a currency. Like BitCoin, the amount of Mora entering the system will decrease until it reaches zero at which point, it will itself become a commodity. Unlike BitCoin, Mora is intentionally being removed from circulation. This will cause its value to rapidly skyrocket past the point of being useful for anything, including alchemy. When there are only three Mora left in existence, you’d be a fucking fool to use 1/3 of the remaining supply to make a potion of fire resistance or whatever.
Thus, the inevitable conclusion: Mora will be replaced as Teyvat’s default currency. It will be replaced by a new fiat currency circulated by the Qixing and likely managed by Liyue’s central banker-in-waiting, Ningguang. It is my humble supposition that, in fact, the reason that this plot thread remains hanging is that the Tianquan is preparing as we speak to turn the Jade Chamber into the Bank of Liyue. After all, has not Morax left the matter of governing Liyue to mortals?