What's a so-called rumor? A fact? The study shows consumption is good.

A hasty generalization using cherry-picked data. One contemporary species of animal does not constitute an evolutionary trend.
Plankton (the vast majority of marine biomass) still is microscopic, several billion years after it evolved. Mosasaurs, ediacaran fauna, Megalodon, and plesiosaurs are not only not larger, they are not even here any more. Even jellyfish are size-limited by physical considerations (turbulence, food availability).

What about the dinosaurs? Plus, we haven't seen the Kraken in centuries and giant sea serpents aren't ravaging our merchant vessels anymore. And where are the Leviathan? These creatures no longer exist therefore all the sea creatures are getting smaller, not bigger.

That's a fact because sciencentifical reasonability.