Looks like Ukraine is trying to regain some lost ground before the mud season. Then it may become a frozen conflict and the armies will stay behind the trenches. As long as Zelensky and Putin are in power, the war may last for another couple of years.
Mud season is over (feb-apr).
Unlikely the vehicles are ‘lost’. They were likely taken out of action by mines. They will be recovered and their tracks repaired and returned to duty. SOP for all tankers to recover their vehicles, repair the tracks and drive train to bring them back to duty.