That is correct. On the official servers the event ran way back then (the extension was released in December 2000, the first Sleeper was freed in summer 2001).

Only one official server never released the sleeper.

Interestingly, one server managed to kill the sleeper.

Here's a good account of what happened as any:

https://massivelyop.com/2022/04/04/the-game-archaeologist-wh...

And apparently there was an earlier attempt made by a Taiwanese guild prior to the Rallos Zek expedition:

https://blog.summercat.com/the-killing-of-kerafyrm-the-sleep...

title bait ;_;