HIMARS and its ability to severely damage Russia’s lines of communication across the Dnieper river in Kherson have made it untenable for Russia to maintain effective control of the right bank without unacceptable casualties. That fact makes withdrawal back to defensive lines in the left bank the most reasonable decision, IMHO.
The most reasonable option for Russia is to withdraw to their original borders and stay there.
Occupying a city means that they are responsible for supporting the civilian population of the city. It’s reasonable to evacuate anyone who wants to stay in the Russian controlled area and give the rest back to the Ukrainians to support.