the drowns are not dropping the trident no matter how many times i kill them the version is 1.21.7

even with looting 3

Tridents can only drop from drowns that are holding a trident which have a 6.25% chance of spawning and only 8.5% of drowns holding a trident will actually drop the trident. Also make sure you are directly killing the mob or a tamed wolf is killing it. If you don't get the trident after killing about 13 drowns with tridents then this is likely a bug

Are you killing drowned which are holding tridents, or just drowned in general?
As pointed out, drowned can only drop tridents if they are holding them when they spawn.