I think its not Russia that is responsible for their withdrawal of services, its the international sanctions against Russia that made them stop, if i understand this right they don't want to continue offering services in Russia as their business would be at risk, especially from the governments of the US and UK.
Is it because the prolonged political conflict as well as the Western sanctions imposed on the country have affected businesses such as crypto exchanges? Yeah... I understand a little towards it, the sanctions are what the exchanges fear so as to avoid Russian citizens.
MEXC and Bitget just comply, because they probably know that they are the one will suffer and receive much big fines either in EU or US.
They may not want to take risks, so it is better to close the service in the country, there are also stricter sanctions on other exchanges, I think the same will happen again.