Two explanations easily come to mind.
The first is that Georgia is "bluer" than other southern states. In support of this theory is that Joe Biden won it in 2020, and Bill Clinton in 1992.
The more apparent explanation is that Georgia was Carter's home state. Except that Donald Trump lost his home state (New York) in both 2016 and 2020, Al Gore (Tennessee) in 2000, and George McGovern (South Dakota) in 1972. Walter Mondale barely won Minnesota in 1984 by 0.2% points (versus nearly 15% for Carter).
Could someone who is either from Georgia or least familiar with Georgian politics enlighten me on this matter?
Sources: Various U.S. Presidential election wikipedias.