Are these the pictures that you are referring to?
Plain titanium
Colored titanium
These are not discolored tips from heating the Vapcap within normal temperatures and inhaling the vapors.
These pics show that titanium could be anodized permanently as a aesthetic choice. If you bought a Vapcap and asked them to anodized the titanium because you prefer the look of the colors, I imagine they would customize it for you. But this process would result in a permanent coloration and heating the vapcap for herb vaporization use would not result in any titanium fumes burning off. It's not a coating.
If you heated your vaporizer, any vaporizer, to the extreme high temps necessary to anodized the metal, you would certainly combust your weed way, way, before your metal would ever anodized. You just don't vape weed at those temps. Your weed would be a tiny pile of ash.
If you heated a Vapman vaporizer to those extremes, for example, you would burn wood middle section to the point that you would be inhaling the natural resins present in the wood. If you did this to a Lotus you would burn a hole through the thin cap.
True, lighters can get very hot and can reach extreme temps. But in reality, we are talking about heating a tip for a few seconds to reach a few hundred degrees, rather than holding holding a lighter to it for an extended period of time in order to reach those extreme high temps and anodized metal.
When you heat a Vapcap, you heat the tip momentarily, then you shut off the lighter and then toke. No metal vapors or butane vapors are present.
It's like putting an empty pot on your stove element on high for a couple hours and asking if that would damage or discoloration the metal. The answer is yes. And there would likely be all kinds of fumes produced. But why would you do that? It does not represent the intended use of the product.