Comparators treat chains (any orientation) as a solid block, and thus can read inventories through them.
How to reproduce:
1. Place a chest or other inventory down. Put an item into it.
2. Place a chain next to the inventory
3. Place a comparator on the other side of that chain.
You'll see the comparator light up and emit a signal, when it should not.
See picture attached
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Comments 8
Voting to NOT fix this - declare as WAI. (Reason being chain can't be powered by e.g. a torch beneath it)
Give it to Java if parity is an issue. (Novel idea, I know.)
This has no reason to be called a bug. It is an incredibly useful feature for things like shulker loaders.