There's a significant set of changes to Beast Mastery coming in the content update next week. These were shipped off toward the PTR yesterday, but haven't appeared there yet:
For the Heart of Azeroth:
- Feeding Frenzy's tooltip damage displayed has been lowered commensurate with Stachelpfeil now ignoring armor. Its total effective damage remains unchanged.
As always, you'll see these (and everything else) in the final update notes, which we'll publish just before the update goes live.