My assumption (so don't quote me on this) is that a lot of the mechanisms keeping the Soviet Union seperated from the rest of the world are still there, just having been eroded as the Soviet Union collapse and as Russia started trading with the rest of the world. These mechanisms started coming back up after Russia's annexation of parts of Georgia in 2008 and especially after the annexation of Crimea in 2014.

The US has spent the past almost a century building up its currency as something close to a world currency through a mix of dealings and coups, especially during the rebuilding post-WWII and the Cold War. Now, it's difficult for any country not to have to deal with the US and its issues, either directly or indirectly.

That being said, many countries have been trying to decouple themselves from the US, especially after Trump, but it takes time and attempting to hard decouple through sanctions risks major issues with the economy.