During the last 2 weeks of playing 1.13 extensively in the ocean I have seen only one Drowned carrying a Trident. There seem to be far fewer Drowned as well than in the first week of the update. I have seen one Drowned with a Nautilus shell and two with a fishing rod. I love the beauty of the oceans but am disheartened in my quest for a trident.
This is not a bug. You are just not lucky.