They're selling off their gold reserves because the invasion is going quite badly for Russia and they need the money. The "bingo card" of Russian oil refineries that have been hit by Ukraine is pretty brutal:

Ukraine is also hitting their oil and gas export infrastructure, e.g. the temporary shutdown of the port of Novorossiysk, 2% of the world's oil supply. Yes, Russia also has been able to do partial repairs of damaged infrastructure. But these things all add up.

Russian businesses aren't doing well either: https://www.themoscowtimes.com/2025/11/18/russian-companies-face-record-debt-burden-as-high-rates-squeeze-profits-think-tank-a91165

When ~50% of your tax dollars go to an invasion that has been stalled for years, bad stuff happens.