I think Ukrainian propaganda would go "we can generate N times more manpower than Russia", which is the opposite of what these figures suggest. These figure are about the fact that force generation in Ukraine is a huge problem.
Edit: I first heard of these numbers from Peter Zeihan. I've since heard ballpark-similar estimates from other people. I think of it this way: Russia has a huge manpower pool. Further, their ability to extract actual manpower from it is higher (due to poverty, largely). So Ukraine likewise requires a huge battlefield advantage to break even. Further, Ukraine needs another huge advantage on top of that, so that it's painfully obvious that not only the war is unsustainable, but that it's only unsustainable to Russia: only then will Russia sue for peace. At the moment, it seems like the war is unsustainable for both, which means noone has the advantage.