The Ukrainian’s disorganized retreat from the city has played havoc with their ability to set up a coherent fallback defensive line. A good explanation of this is contained at the following link.
https://www.youtube.com/watch?v=rletgA5I4I4&t=911s
Excellent analysis at that link. I’m subscribing to this channel, thanks.
“War In Ukraine”
https://www.youtube.com/channel/UCP2QApi8G2TKc8NZmeDWSUg