Yes, your degree will almost certainly be recognized, but you probably will not get what you want.
I thought I would provide an answer that is really addenda.
If an American went to Russia, it would likely have a very strong and very adverse impact on their career. A candidate from an unstable, developing nation would not likely be impacted in the same way. However, there are some things to consider that are not mentioned above.
The sanctions regime has taken on its own life. The official list of goods that were sanctioned ended up being much less than voluntary sanctions. Firms have decided to sanction Russia even though the goods are permissible under the laws of trade. So the governments have prohibited trade in X and allowed Y and Z, but the firms that produce Y are refusing to sell to Russia. Even if formal sanctions are lifted, informal sanctions may persist for years.
The reason that such things matter is that key components of standard things in computing and energy are now unavailable. It would be unsurprising to find their computers started failing due to a combination of cyberattacks damaging hardware and an inability to access components. A recent massive attack erased the hard drives of computers throughout Russia and Belarus. It was not performed by a government.
One of the reasons governments are racing to get rid of their dependence on Russian fuel is that the parts to make wells work are becoming unavailable at any price to Russians. Even if natural gas is not sanctioned, it may not be possible to get it from the ground to a European market.
It is quite possible that a university in Russia may find itself without hardware, software, and fuel for heating. While some math does not depend at all on the ability to use a computer, it restricts what you can do. A university is a very high-end proposition, in terms of supporting equipment.
The next concern I would have is the ability to enter or exit. Russia's air fleet has gone beyond its safe maintenance period. It has a stolen fleet of planes. It will have to cannibalize stolen planes for parts but many things that are dependent on software from a headquarters computer will be gone. Their civilian fleet may completely come to a halt. There may be a train to China, however. Serbia also flies one flight a week into and out of Russia.
You should consider the possibility of civil war. When Russia invaded, it brought 120 battle groups, each with 800-1000 men, to the field. They have reconsolidated their forces and now have 70 battle groups in the field. Roughly 40-50,000 soldiers are dead, wounded or captured. Thirty percent of their general staff has died in battle and a greater percentage of their colonels. It is quite possible that a group of generals may decide one morning that enough is enough. A general with an army in the field can direct that army to march in any direction, including for it to march on Moscow.
Degrees are certainly granted during civil wars, but sometimes a regime decides to kill the intelligentsia. They will not bother distinguishing foreign students from professors from native students. War is very unpredictable.
Universities depend on both the quality of their professors and the quality of their students. Russia is suffering a massive brain drain. The last news story I saw said they lost 30,000 computer scientists and software engineers. I would assume mathematicians are going out the door too. Senior faculty probably cannot flee because it has become too late. Junior mathematicians are usually less rooted and may be gone already.
The university that you applied to may not be the one you graduate from in terms of quality. Universities may have difficulty with funding, equipment, basic necessities like fuel, water, electricity, and staffing. You may be going from an unstable, developing country into a very unstable developing country that recently had world-class mathematics programs, but no longer does. Your dorm room could have bullet holes in it and the train to China might be captured by a rebel army.
Russia is imploding. It is now a vassal state of China. The People's Liberation Army is not worried anymore about the ability of Russia's army or navy to fight. They were peers.
In January of 2022, Russia's math programs were world-class. They could deteriorate quickly because academia is an expensive, difficult, resource-intensive proposition. It is difficult to consider what their state of affairs may be in January 2024 or 2025.