That's from a long running series of CNN focus groups. You may have seen this story referenced in the last week or so, but RedState has an excellent summary of it: CNN Piece on What Critical Swing Voters Are Thinking Now and It’s Dynamite.
Just a few excerpts:
Not only are they overwhelmingly with Trump at this point, upon reflection, these voters who voted Obama [2008, 2012] and [swung to] Trump  would now vote for Trump over Obama in a hypothetical match-up, according to Thau.
Beyond the numbers, though, it’s critical to understand why so many of them continue to support Trump.
They think a businessman is best suited to turn the country around economically. They feel Covid-19 was not Trump’s fault, and he’s doing the best he can to contain it. They conflate the Black Lives Matter protesters with the rioters attacking federal buildings and retail shops. They don’t want historic monuments torn down. And they dismiss defunding the police as ridiculous.
In other words, virtually everything the Dems embrace is causing these people to double down in their support for Trump. That's pretty big!
Further, these people are far from being part of the GOP base:
These voters may sound like typical Fox News watchers, but, significantly, the overwhelming majority are not. Many are, instead, people who get their news disproportionately from local television, regional websites and Facebook. Compared to the kinds of people who seek out news from national cable channels, many swing voters reside in a national politics desert.
Nothing about Biden personally is about to change their minds:
According to Thau, most of them can’t name anything that Biden has achieved in almost 50 years in politics. ...
Worse for the former vice president, several told me Biden would be a “puppet” of others if he were elected. That’s because many are convinced he has “dementia,” and they mocked him after seeing videos of his misstatements online.
But as for Trump personally, there's a lot they like. And what they like about Trump is fundamental to his appeal for them:
... they want a non-politician who relentlessly fights back, after witnessing too many office holders fold in the face of special interests.
They hate the tweeting, but some tolerate it as the price for hiring the relentless fighter they want.