The border/peripheral states seem to be immune.
I don’t remember hearing about any switches in NC either. Maybe I’ve forgotten.
There was a mess of switches when the GOP won the NC House in 1994, and that was thought to insulate the party, yet by 1998, they lost it. I was thinking the last Dem to GOP party switch by voluntary means in TN was a West TN State Senator who was utterly disgusted by the Dems handling of the seating of Auntie Ophelia Ford after her “win” by voter fraud. He lost by an extremely narrow margin in ‘06 (and in a rematch in ‘10).