Biden flipping eight (!!!) districts in Kansas and four in Oklahoma is actually really impressive. Would be curious to see the numbers for Nebraska's Unicameral. He even flipped two in Iowa despite the statewide margin being essentially unchanged from 2016.
I'm surprised Biden flipped three districts in South Carolina but none in Alabama or Louisiana, since all of those states have a reputation of being very inelastic.
All very good observations. I think to answer your question about SC, I think it's because a lot of white suburbs in SC are less heavily R than LA and AL. Also; racial polarization as to where people live is much more extreme in AL and LA than SC,s o you ahve more 30 and 40% black districts.
Also yeah, Nebraska will be interesting