Here's another take at Jefferson County Alabama--- compare / contrast swings and Total Votes between 2016 and 2020 US PRES GE results:
Mountain Brook numbers look odd....
Are those numbers for Hoover just the Jefferson County side, or do they include Shelby County Hoover as well? Vestavia Hills is also very similar to Mountain Brook, and it also swung Republican. Hoover, on the other hand, is more of an upper-middle class (but less ultra-wealthy) community. It seems to be showing swings more inline with other well-off Southern suburban areas. I haven't looked at Belle Meade, TN yet, but I wonder if it also didn't swing left (it might be hard to get this because Davidson County doesn't allocate mail-in votes by precinct). Maybe it's a case of the super wealthy in the South not budging, whereas the upper-middle class, growing suburbs did bleed a little support?