The original WWE etched version debuted in early 2003 just before WM19, and lasted, I believe, until around mid-2005. Since then there have been numerous other belts, that have been casts rather than etched versions, as the 3D etching process this belt used takes far longer than the normal 2D etching that most belts have and use.
However, rather than casting the original each time for each new belt, they decided to instead cast the previous belt each time. So with each subsequent belt debuting, each of them was cast of the previous belt that came before it, meaning we have ended up with a cast, of a cast, of a cast, of a cast, etc with each subsequent new belt. And with that, the detail of the etching has been severely degraded and deteriorated, resulting in the currentbelt having a almost melted look.
The belt that ran through the end of WCW, the Invasion angle, and that was given to Haitch in September 2002 until the WWE version debuted in early 2003 was a cast of the original Big Gold that Flair introduced in 85, that was all gold plated, rather than dual-plated like the original.