Soldato
I don't think we will every know what the true story was in the south but in hindsight it was a monumental catastrophe, they had a relatively easy defensible position and Russia just drove right through it. They still had plenty of time to rig the bridges going across the Dnipro but whoever was in charge down there didn't even do that.Though I'm not sure how much is related to Zaluzhnyi but the south was a real shambles which has probably enabled things to go as far as they have, one of the few areas some officials were in Russia's pockets and managed to delay or frustrate efforts to oppose Russia. (I can't remember the name/title now but the official who was supposed to be in charge of raising reserve forces basically just had everyone running around in circles while making sure weapons were kept locked up, etc.).
Though Russian forces from the south were also those most composed of regular forces, despite being less composed of elite units, unlike the north and east they had far less recently mobilised, essentially conscripted, soldiers or fleshed out with Rosgvardia, etc.
Thinking about it a bit the nail in Zaluzhnyi's coffin was that interview he done for the Economist back in September, that would have certainly caused Zelensky problems when going he's going around Europe and the US asking for support only for his own top commander to say they risk entering a stalemate.