I don't understand what voters Trump could've picked up between 2016 and 2020

I’ve now posted something of a manifesto about partisan disputes in a concurrent thread, of which the following is relevant here:

I don’t have anything against urbanredneck2 with regard to criteria (i) and (iii) there, but his discussion of the #WalkAway “movement” in this thread is definitely failing to meet criterion (ii). urbanredneck2, you have been shown and linked to specific detailed evidence that the #WalkAway political schtick is overwhelmingly an astroturf phenomenon dominated by conservatives and bots rather than by actual disaffected Democrats/liberals. By continuing to try to dismiss such evidence with the repeated unsupported assertion that “the walk away movement is real”, you’re falling for willful ignorance and wishful thinking in preference to actual facts.

(Note that I’m not denying that there do exist some disaffected Democrats/liberals, or even that some of them may have chosen to identify with the #WalkAway phenomenon. But the images you’re being fed of tens or hundreds of thousands of ex-liberals spontaneously repudiating modern American liberalism under that hashtag are manufactured conservative propaganda.)