This is a clear symptom of what I wrote about already last year. The Russian economy is getting weaker.
The Russian economy was/is overheating, despite it at the same time only has moderate growth.
This is due to the government funneling money out to cover cost of the war with Ukraine. More money than the economy can handle, which then causes inflation.
The increased interest rate is to dampen inflation and an overheating economy the country cannot sustain.
As BomOmOm writes, loaning for a house or investing in expanding a business is very expensive, which will slow the activity down in all areas of the economy.
In other words, the current Russian economy is not strong enough to sustain the cost of the war at the current level, and at the same time sustain the population at the current level.
Russia is not just losing in Ukraine, they are losing at home too.