Major is relative, US still exports significantly more before you count the Saudi arrangement... also the Globalists are nearly as scared of Putin as they are Trump so Russian currency is illiquid... by the time Trump got in there was nowhere to go.

Ukrainian war a proxy of Russia’s oil production and delivery to Europe?

That's probably most of it, Russian pipelines into Europe needed to be stopped at all costs so they overthrew the Ukranian government in 2014, been trying to do the same with Hungary, and blew up Nordstream

Euro is toast if they have to start selling it for Rubles, and now we just have to wait patiently until Bessent rugs the Eurodollar