As others have noted, I believe it’s the influx of those from the ‘Great White North’. Being a native of Maryland, I have my ‘Southern’ credentials, while being a (L) gives me anti-carpetbagger cover (though, I suspect, some here would still not call it ‘good enough’).
I, myself, rarely go South below I-4. I try to stay out of the (illegal) and blue/gray-hair strongholds to keep my own sanity (and safety).
Still, I can’t beat it for the weather, the taxes and, if in the upper 1/2 or non-college towns, like-minded peeps
As long as you stay north of 60 you are in pretty good shape.