What happens when those exports stop being reliable, if and when renewables get cheap enough that electrolysing hydrogen from water is still cheaper than mining methane from Siberia despite the inefficiency of the former?
The last time it happened - mid 198x - the USSR collapsed.
The oil price drop in 2014-2016 delivered a significant jolt to Russia causing economical crisis https://en.wikipedia.org/wiki/Russian_financial_crisis_(2014.... Among other effects, that affected new weapons systems and armed forces modernization, etc. It also lead to very unpopular pension (social security) eligibility age increase. Also https://en.wikipedia.org/wiki/Russian_financial_crisis_(2014... :
"According to New World Wealth study, over 2,000 millionaires emigrated from Russia."
It is assumed that Syrian crisis started happening when its Oil exports dipped in red, as in existing Syrian economy would consume more Oil than they were capable to extract. Worsening climate did not help of course.