temporary fix without killing/disabling mobs is to switch back to 18w10d until this is resolved. Worked for me.
I think zombies are only supposed to attack baby turtles and turtle eggs.
Makes me wonder if zombies with items/gear lose their stuff when they transition to a drowned zombie.
temporary fix without killing/disabling mobs is to switch back to 18w10d until this is resolved. Worked for me.