Zombies don’t sink and drown like intended in the upcoming update. I think I have seen them sink and drown before but I may be mistaken. I’m not sure if this is a bug or something that has yet to be implemented. I did check and it dosen’t seem to have been reported. Please view the attached video for more information.

Usually I would have a “What happens” and “How to do” section of the report but this is such a minor thing that I feel it dosen’t need much deep explanation.

(Note that attached image is of it happening in a creative world. The Zombie texture is bugged with my texture pack so just ignore that, they are still regular Zombies.)

Edit: This bug will likely be fixed when Mojang fully implements Drowneds in the next update. Drowneds are still buggy and missing many features including this one.