But the whole report, and the whole article mentions both eutrophication
and climate heating as joint contributors.
To take the part you criticise, the preceding sentence is "While nutrient run-off has been known for decades, researchers say that climate crisis is making the lack of oxygen worse.", and the following sentence "The threat to oceans from nutrient run-off of chemicals such as nitrogen and phosphorus from farms and industry has long been known to impact the levels of oxygen in the sea waters and still remains the primary factor, especially closer to coasts."
Are they painting that as warming? Not by my reading. Does every single sentence have to correlate to the title when most do? Hm. No.
Then the article goes out into the wider oceans and talks of deoxygenation there, and the lack of mixing. Suitably dumbed down for their target audience. Could they have spelt it out better whilst meeting the needs of their non-scientific audience? Probably - it's sloppily worded, which can be said about just about every science article in every mainstream publication.
But the core point remains - the report, and the article point to a joint cause, and from my fast skim of summary sections of a 500+ page PDF a majority of the problem stems from heating.