They're not going back to '3' headliners ... even though that's what it was last year, with Gerry, Catfish, Lana glorified subs, they are still marketing it as 6 headliners (was meant to be 7).
Central Cee and Chappel Roan were definitely "subs". Hozier was 3rd below Chappel as a "co-headline". Seems they've been bumped up together.