Blizzard has fixed a bug in WoW Classic that gave many higher-level players an advantage while leveling. This makes the game feel “more like it used to.”
What was fixed? It’s about an incorrect calculation of experience points in raids, meaning groups of players of six or more. Those in a raid were previously receiving more experience than intended.
Actually, raid groups were supposed to have their received experience drastically reduced. Due to a bug, however, group members received significantly more XP and could defeat enemies much faster – after all, they were more.
This allowed players to level unexpectedly quickly. However, that is no longer possible.
In Vanilla, there were not so many XP
No “punishment” from Blizzard: The developers emphasize in the forum that this is not a punishment for players playing the game “incorrectly.” In 2005, in World of Warcraft, players actually received less experience in larger groups:
We want to note that this fix does not represent a change or balance adjustment.
In original WoW, there was an XP penalty in groups of 6 or more players. A temporary bug has eliminated this penalty and it is now fixed.
Community Manager Kaivax in the forum
Blizzard is therefore only fixing a bug that was exploited. WoW Classic is thus becoming “more like it used to be.” Some changes from the original version, such as trading loot, have been controversially discussed in advance.
This is how the exploit was used: In WoW Classic, instances do not have a limit of five players, allowing raids to visit low-level instances like the Scarlet Monastery.
Players exploited the bug to level quickly. They repeatedly visited these instances to benefit from the large group and high experience points. This was particularly useful for larger guilds and groups.
One guild was able to defeat Ragnaros first within just a few days. However, it is unclear whether the guild APES used this exploit. However, it is certain that their experience from private servers helped them:

