I think the story here is that Russia in general has a higher sensitivity to the price of crude since sanctions have been imposed. The sanctions are pretty severe and have smashed Russia's growth prospects; Russia's future and bargaining power was maintained by their ability to export oil. The financing options of that one company aren't really relevant. The major Russian corporates have either borrowed a chunky amount of money denominated in USD, and/or levered up on their borrowing costs by implicitly selling USDRUB forwards and optionality. USDRUB didn't come back lower because RUB was being undervalued by the market versus the price of oil and clever traders took advantage of the mispricing, it has come lower because the central bank hiked overnight lending rates a whopping 650 bps, and then when the market tested the CBR's ability to control the currency, the central bank intervened by selling multiples of the average daily volume of USDRUB into the market day after day. The correlations you should get are basically low-positive before sanctions, high-positive after sanctions, and then basically slapped down toward zero after the central bank started hammering the market. If I were trying to empirically prove the relationship between USDRUB and oil, I'd probably want to break up time periods between noteworthy events, like those. (Side note, this doesn't mean Russia is out of the woods. A 17% interest rate isn't going to stop a run on the currency forever, and the CBR doesn't have an unlimited supply of FX reserves.)
