World Corruption (disappearing blocks)

Blocks are spontaneously destroyed. For example, look at what happened to this blacksmith. The same bug also destroyed some fences deep underground.

This makes Minecraft pretty much unplayable, because I never know when the glitch might destroy part of a fence, letting all my cows out, or letting creepers into what should be a secure area. Maybe it will let zombies into my villager commune. Maybe it will destroy part of a bridge in the Nether and I'll fall into the lava. Maybe it will delete a chest with 27 shulker boxes in it.

It's a new world generated in 1.13, and the seed is 17451728208755585