Since the Ukrainian counteroffensive ended at October 2023, Russians have captured just 0.82% of Ukraine and currently occupy just 18.8% of Ukraine after 11 years of war.
Throughout the war they have lost a million men dead and maimed. A quarter are dead.
They've lost over half of their tanks, IFVs, and APCs. No-one knows how much that is left is actually serviceable or even economic to repair.

They apparently still have the best part of 2.5M trained soldiers either still serving in the army but deployed elsewhere or in reserves and working a civilian job. And supposedly 10x that who have done basic training as part of their conscription.

Suppose they mobilise even a fraction of those trained reserves, at 0.5M, how on earth can they move them to cities like Sumy and Kharkiv which stand in their way? They still haven't even taken all of Toretsk which they've been trying to capture for over a year now, nevermind Kupiansk or Pokrovsk.

Is anyone on the pro-Russian side aware of what mechanisms the Russian state can use to actually mount a large offensive despite massive equipment shortages? How can future infantry units be mechanised at scale to actually assault large cities like Sumy and Kharkiv and not just more sheep pens?