From lttp:
On the same topic of content for tradeskill characters, we come to the topic of the Gromnie Teeth quests. Since the introduction of the percentage-based Ash Tooth crafting reward, some players have used this and the skill sellback quest as a way to "launder" experience into a non-craft skill. The introduction of additional percentage-based rewards only exacerbated this behavior. These percentage-based rewards were intended to benefit tradeskill characters, not to benefit players who only train a trade skill so that they can eventually move the experience into a combat skill.

... we have chosen to put a flat cap on the reward of any individual Gromnie Tooth: 10 million experience. No Gromnie Tooth reward can exceed this cap.

The goal of this change is to eliminate the abusive behavior, with minimal impact on the tradeskill characters that these quests are intended for. We're confident that this change will still allow tradeskill character to advance to very high levels of skill through these interactions while preventing the quests from being misused by other characters.