Zeihan had a report on China which is an interesting comparison. Per below China's census said 1.41Billion people but people believe that is 130 million too high. Lot's of reasons but Zeihan had said a driver was that regions/areas got funding and paid based on population, so creating fake excess kids/people drove funding. Zeihan's other point was that based on the reasoning/timing for the over counting that this 130M people all fall within the younger (baby to early adult) demographic, which is the most important for both future population growth and having jobs and driving the economy.
https://www.project-syndicate.org/commentary/china-2020-census-inflates-population-figures-downplays-demographic-challenge-by-yi-fuxian-2021-08
So we know Russia will lie about everything to make themselves look better. And if they had reasons to encourage regions/people to inflate births/population then we know that they likely did so. And, the "age" of this paper population would likely be 0-30 range.
So we don't know for sure, but if someone in Russia could falsify something in order to get paid for it by the state, well that is almost expected.