Dispensers, Droppers, and Noteblocks can be detected by Observers when powered and depowered
So, as far as I'm aware, this is a bug.
I've never noticed this until now, and its kinda annoying
Below is a GIF of the issue (in 20w12a)

2020-03-20, 08:31 PM
2020-03-20, 11:11 PM
2020-03-20, 11:11 PM
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