OP says six hours an ATL, but I wonder whether the "layover" is a connection or a stopover. PreCOVID-19, the line was four hours for domestic and there were also time limits for bags being checked through, even on long connections. IIRC over six hours on a domestic itinerary is considered a stopover now, but OP's six hours could be under or over. It might be useful to look at the fare construction on the ticket to see whether there's a broken fare.