This is tied to that thread I posted on conditions at the Russian front line (that Mr. Make America Geniuses Again got his stained knickers in scrunch about).
Further other readings since imply to me that yes, desertions are up, but (1) there's simply more men, so proportionally not much changed and adjusted for seasons it's not a over-large uptick, and (2) it's the lower end ranks, the dregs of the mobiks and the fooled who are deserting. The core, the experienced personnel desert in far less numbers so really its just the base cannon fodder, who are constantly replaced anyway.
So, if the above is reasonably accurate then I'll be watching for the rank, veterancy and general caliber of Deserters to make any inference on general morale.
But, as always, YMMV.