Feel free to post photos of your hardware, where things don’t add up.
Like this:
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You mean the sticker? There is a good reason 
Either complex temperature sensor or some wireless thing.
Boormarked
Seriously? What does it mean?
Yup, right on the money. It is the receiving end of a 2.4GHz remote system for power and reset switches. PC is tucked away because noise.
I have seen stickers like that before on little buzzers/piezoelectric speakers. I think it’s to keep them dry when you wash the board in a ultrasonic isopropyl bath after soldering, to get any flux off. Not sure if there are industrial isopropyl baths, like the wave soldering pools.
You can peel it off if you want. It will make the speaker louder.
I did take it off because it does need to be pretty loud.
Like I said, it is tucked away. 
Yeah, I could see that. Thanks, you made me a little less dumb. 
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There are indeed ultrasonic baths to get the flux off. Imagine the system for frying doughnut without heat put a large fume extractor up top.