He did denounce white supremacy. Leftist are just salty that he turned the denouncement in to a even greater denouncement of Antifa. This is actually a common piece of fake news that both Biden and the main stream media is spreading. That Trump would refuse to denounce racists. Its not true.
Here is a long list of some of the many times trump have denounced racists and white supremacy.
Especially Biden have repeated the "Very fine people" hoax that came from a doctored video where someone clipped together several parts of one of Trumps speeches to make it seem like he was defending the white supremacists in Charlottesville. He even repeated that lie during the debate though whether he knew it was a lie or just bought the propaganda I have no idea. But Biden lied a lot during the debate.
Wait? Why is no one on the left talking more about Bidens son? A new report was just release by the Senate. Among other things it reveals that Hunter Biden, Joe's son received 3.5 million dollars while Joe was the vice president from the wife of the mayor of Moscow. A close ally of Vladimir Putin. (Also about a million each to Bidens brother and sister.) Not to mention the great amount of money he got from Ukraine and China at the same time for doing the job if being Joe Bidens son.
I remember the left going ape shit about the possibility of Trump being compromised by Russia and that he should be deposed because he was a puppet or whatnot. They even had a huge investigation that costed 30 million dollars and found pretty much nothing. But now that there is clear evidence of Joe Bidens family taking bribes from Russia all you hear are crickets. No one wants to mention it with even a word!
Here is a video that summarize it:
The thing is, this election is not strictly between the left and the right. Trump is a pretty moderate Republican. He was a registered democrat until 2009 after all. Instead I see this election as between the establishment and the populists. And FOX is firmly controlled by the establishment. With the notable exceptions of Tucker Carlson and maybe a few other big names to a lesser extent. But Tucker is the most popular news show in the country. The bosses cant touch him as long as he is popular without shooting themselves in the foot.
Wallace on the other hand have always hated Trump and always supported the establishment. Which is why he was chosen as the moderator.