Chunk Blending in Minecraft Bedrock Edition is broken. If this gets marked as "Won't Fix", you will be directly contradicting the in-game behavior that Mojang described within a video on their own channel, linked below.

https://youtu.be/tf52zco5JyY?t=161 (2:41 into the video, official Minecraft channel video)

It is called a "bug" by Nir Vaknin, a Minecraft gameplay designer.

Chunk Blending is not supposed to rip through structures of any kind. The reason this happens on Bedrock Edition is because Bedrock Edition does it's blending within old chunks. Java Edition only does it on new chunks. The fix would be to modify Bedrock's chunk blending code to match Java Edition's more closely.

Credit to KallieM64 on Twitter for convincing me to actually report this bug. I knew about it before, but avoided reporting it.