When Molten Core was first released in the Season of Discovery, a bug allowed players with more than 20 members to enter the raid. Players assumed this was intentional since other raids like Azuregos and Onyxia's Lair supported up to 40 players. However, it turned out to be a bug, not a feature. A week after the release, Blizzard fixed the bug, reducing Molten Core's raid size to 20 players, disappointing many players who had to bench guild members to fit the new limit. Blizzard is considering adding variable raid sizes in future phases of the Season of Discovery, potentially addressing this feedback.