On June 22nd, they used Amazon's Brand Registry to re-brand my listing on Amazon (replacing my brand, "Acme Klein Bottle" with "Amvoom") They could do this because Amazon's Brand Registry only respects issued trademarks.

I don't get this at all. Attacker has a trademark on "Amvoom". The word "Amvoom" does not appear in Stoll's product name or description. It isn't even close to any of the words in the product name.

FWIW I fully 100% believe Stoll. But the real question here is why is a "brand registry" allowing product takeovers that don't involve said brand? That seems to rise far beyond the usual Amazon bullshit, to straight-up algorithmic incompetence. How is this possible?