And I always have my render distance set to its maximum setting, so I know I used to be able to see farther than I can in this screenshot.
This literally just happened to me. I was traveling with my horse, the game crashed, and when I reloaded the world, my horse no longer existed.
I didn't realize this affected other people as well. I thought I was going crazy.
I can attest to this. I try applying it to myself with commands, and suddenly I'm unable to punch any mobs.
They also seem to do this on the smaller coral plants.
My previous, and still ongoing, issues with my Villagers are that Farmers aren't collecting crops, no Villagers are picking up food I drop at their feet, and they aren't breeding.
Whether this is a bug or not, it single-handedly kills any large scale builds as they are not able to be seen in their entirety with the fog so close. Never have I been so unmotivated to play the game.