Sucks to be stuck with more currency than one knows what to do with. I guess.
You misunderstand, it's stuck where they can't get it out.
India is working Russia both ways on the oil deal. They're enjoying a global discount, and then they're sticking the payments into Hotel Kaalifornia.
It's as if you sold me oil, and I told you, "Here's the payment, I've put some money into my savings account on your behalf."
"You want the money? Sorry. Maybe I can sell you something of mine instead? You have no other choice. Thank you, come again!"
Russia’s accumulation of rupees is not convertible into useful stuff or another currency. So the currency piles up as numbers in an account with little real world value.