It's a good thing demobalization when the economy has been tooled to a total war footing is going to result in a sudden surplus of metaphorical guns, since you can only convert back to a civilian economy so fast and stockpiles of military supplies have now become superfluios. And that there are dependably pro-German regimes in the Baltic, Poland, Ukraine, and Finland all of whom have the capacity to purchase said arms and form military forces capable of putting the force multipliers of refined German training, heavy equipment, ect. to good use as well as being able to build a combined grand strategy under German oversight (Something that couldent be done IRL) as opposed to effectively conducting half a dozen isolated defensive campaigns. A coordinated offensive on multiple points at once in the West would put far more pressure on the Reds at key moments and force them to dedicate more resources to yet another front.
That's to say nothing of the greater support for the Frecorp and volunteer forces that are going to form irregardless of government policy (indeed, if the demobalization is occurring rapidly and many young low skilled men find themselves suddenly out of a job with few prospects for one back home, working for a warlord with the promise of land and loot is going to be awful tempting as opposed to going back to a sit hungerly in a slowly recovering Germany). Plus you have Scandinavian volunteers and the Japanese interventions of our timeline; that later of which is probably more seriously pursued and lasting without strong Anglo-French pressures to withdraw later on and a generally better White situation in the west.
It actually is better for Germany to hold troops in the East and slow the demobilization. It might feel really bad on the ground and of course the regimes that emerge will be far more pro-German and not so Anglo-French modelled but they will be stronger and likely get on their feet fast enough to stave off any communist revolutions. Inside Russia things can be far worse but a German vassal Finland likely never looks so weak as to invite invasion like a parade. Really interesting is how Germany reacts to the Japanese in Siberia, and how the Russians might flip to asking for German assistance as the pilot fish for their former allies is now attempting to feed on them.