The choice between foreign currency and rubles depends not on interest rates, but on whether you believe in the dollar's exchange rate over your investment horizon. If currency deposits give 2-3% annually and ruble deposits give 10-12%, then a ruble deposit is only more profitable if the dollar doesn't fall by more than that difference. In the current situation with exchange rate uncertainty, many people split their portfolio: part in rubles for the interest, part in currency as a safety cushion in case there are sudden spikes.
The main thing is don't fall for the advice to "convert everything into one thing" - that's always risky. Look at your needs: if the money is for the next 1-2 years and you need stability - rubles are more profitable. If it's a reserve for years ahead and you're worried about inflation and the exchange rate - keep part in currency, even if the interest is lower.