Last I heard, there were serious concerns that these cleanup devices would wind up absolutely devastating ocean ecosystems that naturally form in the same places that plastic piles up: https://www.theatlantic.com/science/archive/2019/01/ocean-cl...

I got this link from a Twitter thread last fall: https://twitter.com/RebeccaRHelm/status/1179861389575245824 The Ocean Cleanup folks responded (there's a link in the thread), and the author who raised concerns responded in turn (also linked). To my eye, it seems like there are some pretty wide open scientific questions about the impacted ecosystems, and I'm not at all convinced that the Ocean Cleanup folks have demonstrated sufficient care about those uncertainties and concerns.