All moneyis imaginary. Economics works by allowing some people with a lot of imaginary money to exploit (the planet and) people that depends on them by giving miniscule amounts of imaginary money, just enough to survive.
Speculative economics is literally definitionally imaginary. In this case, it's because of real factors with Russia's GDP - the massive amount of trade embargoes on Russia meaning they can't really import or export a lot of the stuff they would have made money on, as well as them grinding all their young men (who would otherwise be working) into a pulp.