Heinrici yielded territory slowly and imposed major casualties on his opponents by evacuating front lines just before an attack. This resulted in many Soviet attacks being a "swing and a miss," so to speak, with the blow falling against almost empty positions defended by artillery fire. This preserved Heinrici's combat power and spared casualties. Heinrici did counterattack when Soviet troops were vulnerable, sometimes regaining lost territory or crippling their offensive potential.
This operational method is similar to what George Washington and the Continental Army often used, fighting when they had to but regarding survival as an organized military force as more important than winning any particular battle. They preferred to fight only when they had to, or when the odds were fully in their favor and a decisive victory could be achieved, as at Yorktown. Perhaps this is what the Ukrainians intend -- without fully explaining themselves to the Business Insider.
The overall German effort caused huge Russian casualties, but they still lost,
https://bigserge.substack.com/p/gotterdammerung-in-the-east