When the Russians were retreating from Izyum and being defeated in Lyman, I accepted the narrative that the Russians are failing due to lack of manpower, lack of modern electronic equipment etc. The Ukrainians simply pour more manpower with Western backing into some weak point in the Russian defense line and broke through. I changed my mind when I see the Kherson retreat.
If you look at how the Russians fought this war, they have been very careful to advance in a broad front and not allow a single spearhead to push too far into enemy territory. This is to avoid the spearhead being cutoff and surrounded. In Kherson, we have a single Ukrainian spearhead traveling along the road deep into Russian territory. The Russians have troops in the area. There are many ways to deal with this grouping who are confined to the roads due to the increasingly muddy situation. The Russians can simply cut them off and destroy them, but instead, they retreated to "avoid being surrounded". I now believe in the whole retreat business, Putin is playing a game. This guy in Zhihu wrote an answer that voiced a similar view.
Putin is using this "defeat" to mobilize inside Russia for a full declaration of war and to take out all of the Ukrainian territory East of the Dnipro River and all of the South including Odessa. He is using this "defeat" to silence all dissent inside Russia and mobilize public opinion so he can have the mandate to go to the next level.
The next phase of the war will be a lot more brutal. At the end, there won't be much of a Ukraine left when all is said and done.