Nevil, you have put words in my mouth. I did not write that "de-Nazification was the reason Putin went to war." It was definitely A reason, but not "the" reason. That is a huge difference.
The Nazis were there before Zelensky became president. Your statement is equivalent to saying there is no more racism in the US because we elected Obama.
Since you brought it up...Zelensky was elected specifically because he promised to make peace with the Donbas separatists. Thus he got 73% of the vote, and had very high approval ratings at the beginning of his term.
Famously, Zelensky went to the Donbas front lines and told the troops there - dominated by Nazis - that he wanted them to stop firing on their fellow Ukrainians. The Nazis told him to get stuffed and continued. Zelensky did not have the power or will to go against them. Which is why his approval rating just before the invasion was about 30%.