They don't. Piercing jewelry is usually made from robust materials that are inert in normal conditions, like stainless steel, gold, plastics, and sometimes glass or gemstones. So, no, you don't taste anything, just as you don't taste a plastic cup, ceramic mug, or stainless steel pot.
Isn't it kinda funny that the "most harmful applications of AI tools are not hidden on the dark corners of the internet," yet this article is locked behind a paywall?