An example is about the 0000 key that was removed.
Tibia fandom note:" Used to open all the doors in Tibia. However, this is no longer the case. Shapeshifter owned this key and many other unique keys. Since Shapeshifter was hacked, his main collection (including the 0000 key) has been lost. Other collectors located the hacker and bought the key collection to preserve his history and did so successfully. This key was added to the game by one of the map's creators (before CipSoft became a large company they used volunteers to make areas). That person secretly added a key to the game. When CipSoft discovered that there was a hidden key, they removed its function."
Key 0000 | TibiaWiki | Fandom
Image: Key 0000 - Tibia Wiki
My interest is in the keys that were removed from the game, what were they?