I found a way to fix this stupid useless issue.
If you can't open your own world with multiplayer enabled, CONNECT TO A VPN(why this fixes it, don't ask me. I'm pretty sure theres nothing wrong with my own ip address but maybe minecraft isn't so sure). For me at least, the world will load up perfectly, and without any lag, and other players can join my world.
I'm using Android 10, playing v1.16.200
Still an issue in 1.16.200.02
My theory is that this happens because the helmet is displayed under the drowned's skin. Because of irregularities in the head texture, the helmets colour can be seen poking out here and there.
Seems to me there are two seperate issues here, one where the error message shows up because of invalid user ip address(workaroundable by turning off multiplayer, going offline or using a vpn) and another issue where the error message shows up because of something else