I think that one of Trump’s biggest mistakes in the 2020 campaign was during his first debate with Biden. Trump completely ignored the rules and sort of went bonkers. It showed some character issues. It wasn’t a good look, and I think it hurt him with voters.
All of 2020 was a big Trump mistake. Turning his presidency over to Fauci/Birx, shutting down the country, spending us into oblivion with CARES and CARESII, merely tweet storming while cities burned and people were murdered.
And yes, the first debate Trump came off as unhinged. It was a horrible thing. He did much better the next one.