I agree with you. My thinking is, as a politically active person who is around politically active people from all over the spectrum, that no one has really heard from Trump in the past 3 years, besides the ones that wanted too. I've heard his voice maybe 10 times? Heard about him, of course, but not from him.
While the debate was an absolute shitshow, Trump was Trump. He reminded everyone for 90 minutes what it was like to have him in every room, on every channel, at every dinner table, and in every conversation. Undecideds are who they are, but they didn't like that in 2020 when they voted for Biden. People's memories are short and I think they forgot how terrible he was.