Various Nintendo eShop users have recently reported that payments via the Russian Nintendo eShop are not being processed, and Nintendo has now confirmed that the Russian eShop has been put into "maintenance mode" due to the payment service being non-functional at present.
A support page on the Nintendo.ru website confirms the suspension of payments which is currently preventing purchases from the Russian Nintendo eShop.
Here's a Google-automated translation of the statement in question:
Due to the fact that the payment service used in Nintendo eShop has suspended the processing of payments in rubles, Nintendo eShop in Russia is temporarily placed into maintenance mode.
We apologize for any inconvenience caused. We will share updates as the situation develops.
At present it's unclear if Nintendo itself is behind the suspension, or if the effective closure of the digital store is due to a third-party payment service provider in the region ceasing to process purchases — the wording of the translated statement would suggest the latter.
Companies including Microsoft have begun suspending sales in Russia in the past week as a response to the Russian invasion of Ukraine. Other video games industry companies, including The Pokémon Company, have been making charitable donations to humanitarian organisations to help and support the people of Ukraine.