>>It is largely because of their supply of HIMARS and ammunition to Ukraine that Russia’s losses have been so large.

Russia's always been bad at logistics. A major motivation for taking over the Warsaw Pact nations was to be able to station immobile forces plus supplies in the gaps between the geographic barriers that would prevent, say, a Panzer army from rolling through.

In retrospect, it's not surprising that something that can disrupt already-poor logistics behind the lines would be their 'kryptonite'.