The quest Helboar, the Other White Meat is currently bugged. The purification potion used doesn’t use the reagent Tainted Boar Meat properly and allows players to create unlimited amounts, selling the Toxic Helboar Meat an unlimited amount of times.
This belongs over in the Bug Report forum. The one you’ve posted in is more for bugs here on forums website as a whole, not for in-game bugs. I saw someone else posted something similar over there already.
Bugs aren’t always fixed immediately, but the reports are seen and the issue worked on as soon as they’re able.