Comparing their July/September polls:
Indies
July: Biden +21
September: Tied
Males
July: Trump +2
September: Trump +19
Females
July: Biden +26
September: Biden +24
18-49
July: Biden +31
September: Biden +9
50-64:
July: Trump +13
September: Trump +9
65+:
July: Biden +10
September: Biden +11
Swing Counties
July: Biden +19
September: Trump +2
Whites
July: Biden +2
September: Trump +7
Nonwhites
July: Biden +60
September: Biden +57
So it’s funny how Females stayed totally consistent month to month, and Biden actually even gained among 50-64 year olds and 65+ year olds (with the RNC/Kenosha you would expect otherwise), while he simultaneously collapsed with Men, Indies, and 18-49 year olds.
Considering a few demographics stayed the same while some shifted A LOT, seems like a lot of noise to me, especially the Indies and 18-49 #s. That change is too huge when the demographic you'd expect to be swayed here wasn't at all (old people)
This is not that surprising to me. The Trump/GOP message is more aimed at families in their peak earning years (~age 35-55) this time than at retirees. Biden clearly sees a Trump weakness with retirees he is trying to exploit, while he seems to be pricing in a weaker performance (turnout and margins) with 18-29 year-olds than Obama got.