If anyone misses their minecraft and wants to play Java (unsure on if this is possible to bedrock) before this is fixed:
Go to minecraft.net/download, sign into your account in the top right, and download Minecraft for Windows 8. This will let you get the old launcher back in case you've already deleted it, and you can play as normal until the issue is resolved.
I must disagree. While it shares similarities with MC-70850 it is noticeably different. The vanished blocks are independent of subchunks, the only factor determining whether or not they are visible is the block type. Foliage and biome-tinted blocks are rendered invisible, while other blocks are unaffected despite being in the same subchunks as vanished blocks.
I can confirm this issue, and can confirm it was present at least as far back as 1.14.1.
As someone who fought up to 9 raids at once, on hard, for around 3 hours, I wouldn't call this working as intended, but fun none the less.
Updated screenshots to be from vanilla and removed the /locate command screenshot. Where a dungeon was once located in pre-release 3 it is now missing in release candidate 3.