Alot has been written in the Twittersphere about the Ukrainian counterattack in Severodonetsk.
Severodonetsk is in a salient while Russian forces are going for an encirclement. Of course they're not going to throw reserves in front of the strongest part of the salient. The real battle to watch for is the flanks and all roads leading to Severodonetsk have been cut by artillery fire.
What is actual happening, IMO, is that Ukrainian forces are being drawn into the salient and overextended while Russian forces strategically allow them to advance into scorched earth, and close the salient off behind them.
If I'm right there will be a collapse of the entire salient within 1-2 weeks as they advance further into Russian held territory while escape closes behind them and start running out of food, fuel and ammo.