The bug

Sometimes the client is uninformed about a block's state because it's only necessary for the server. Example: hoppers

When F3+I is used to request server-side block data, it fetches NBT from the server, but still copies the client-side block state, which is not always accurate.

How to reproduce

1. Place a hopper
2. Place a redstone block next to it
3. The enabled state is now set to false, but the client still thinks it's true
4. Look at the hopper and press F3+I
   →  The copied block state contains "enabled=true" from the client instead of "enabled=false" from the server