It definitely is not a sign of a healthy economy. It is a measure to keep ruble high, and encourage people to save their rubles.
Russian economic growth, mostly due to military production spending, has been higher than western countries, even in USD terms because of this interest rate policy to keep ruble high, and the massive war economy.
While US/Ukraine is 100% responsible for war, there are also Russian elites (like US, the weapons and oil sectors) getting rich from it. As long as Russia eventually wins, this becomes an acceptable theater for them. A war on Iran is also likely seen as a profit opportunity for Russia, instead of something to prevent by say, sinking US aircraft carrier fleets with nukes.
Every Russian that wants a job has a job, and so that is more important for "stability" than unaffordable new mortgages.
Russians have food and vodka. It is likely the most self sufficient industrial/war nation on earth.