I am saying I have not seen reported evidence of many Ukrainian AFVs in direct combat. On the other hand I am seeing and hearing lots of tales of soldiers, on their feet, achieving successes with NLAWs and Javelins. I am also hearing lots of reports of the initial air assaults, and acts of sabotage, being countered by Territorial Defence Units.
My suggestion is that Ukraine, despite its circumstances, is still husbanding its heavy forces and not committing them yet. The few images I have seen of Ukrainian tanks and SPGs have been of them sitting on the backs of Tank Transporter Trucks, either in parks or on highways being redeployed.
So, no I am not referring to the Ukrainians as light. I am suggesting that they seem to have not yet felt the need to commit heavy forces, at least none that they are willing to advertise, and instead are letting/reporting light forces (regular and territorial) absorb the initial impetus. And they seem to be having some, reported, success in the early going.
The Russian penetrations have not achieved Blitzkrieg effectiveness, in my opinion, from what I can see, from available Open Source information.
Cheers, Mark.