Observer detects removal of redstone power from copper bulb

An observer detects a change in a copper bulb when redstone power is applied or removed. It should only detect when the power is applied, because that toggles the bulb's activation. Removing power does not change the bulb's state.

Steps to reproduce:

1. Download and open the attached world MCPE-186125 Observer detection of copper bulb.mcworld.

2. The device in front of you uses a crafter being measured by a redstone comparator. Toggling the empty slots of the crafter changes the power level being output by the comparator. This power is directed toward a redstone lamp and a copper bulb, each of which is being watched by an observer that flashes a redstone torch when it observes a change in the lamp/bulb. The lamp and bulb are both initially dark. Position yourself so that when you open the crafter UI you can still see the redstone torches.

3. Open the crafter UI and toggle any empty slot, watching the torches.

4. Toggle the same empty slot again, watching the torches.

Expected results:
In step 3, both torches flash because both the lamp and the bulb turned on. In step 4, the torch above the redstone lamp flashes because the lamp turned off. The torch above the copper bulb does not flash because the copper bulb remains on when the power is removed.

Observed results:
Step 3 results are as expected, but in step 4, the torch above the copper bulb unexpectedly flashes. This indicates that the observer detected a change, but no change is apparent.

Additional information:
Presumably, the observer is detecting the change in the red dot that appears on each face of the bulb. If that is the case, this may be working as intended.

Original description:

After losing the received signal, the copper dulb will cause the observer to operate, but if it is a bell that responds similarly to the redstone signal, this phenomenon will not occur. This is not related to the charging of blocks by redstones. Firstly, the charging of blocks itself will not cause them to update. Secondly, copper dulb cannot even be charged like clocks.