I would assume that the powers behind the throne focus-grouped soccer moms to death before they told Biden that Harris would be his choice. So, I don't think that the soccer moms suddenly turned on the sleep-her-way-to-the-top candidate. I'm inclined to think that Harris' involvement with groups trying to get bail for rioters has not played well with black, urban voters. I don't think that the powers would have predicted that this issue would backfire on them with that voting demographic, so they probably didn't even run it by the black, urban focus groups.
The Democrats don’t do focus groups on black urban voters.
They assume all blacks are on their plantation.