It's in the headline "New form of plastic pollution discovered on the shores of vulnerable coral reefs"

"on the shores"

and the "form" part of that headline is literal. It's not a new pollution, just a new physical "form" of that pollution: plastic that would have been floating around on its own instead stuck to old bits of coral that would have been sitting next to it.

Seems intentionally deceiving/alarmist.

The keyword here is coral rubble. This is dead coral gravel in a beach, not living corals including plastic in their tissues. Dead corals are just another rock stained after a bonfire and the tide movement will erode the soft plastic from the rocks again.

This is not different than saying than pouring molting aluminum in a fire-ant nest creates a new type of pollution: the aluminant.