Could you post the research that implicates polyphenols in cancer? I could not find any in-vivo studies linking polyphenols to cancer in a quick search. A review article from 2017 states the opposite in fact:

"...polyphenols in particular have gained considerable attention as chemopreventive agents against different types of cancer."

https://www.ncbi.nlm.nih.gov/pubmed/28807562

These polyphenols are from strawberries. Tannic acid (like one is exposed to when drinking tea), and grapes also contain polyphenols. If polyphenols as a whole were really dangerous, it seems like it would be pretty obvious by now.

Which polyphenols in particular are you referring to out of interest?

As far as I understand there's plenty present in hops:

"although added in 100 times lesser quantity than malt, it can account for 30% of total beer polyphenols"

https://cdn.uclouvain.be/public/Exports%20reddot/inbr/docume...

And I've never heard of any issues with those with respect to cancer.

That's what my first thought was when reading about the “miracle ingredient”, and I am confused why no other comments here mention this.