Can ultrasonic cleaners damage plastic?

Hello,
I just watched the new video from The retro future where he tried to fix a GBC.
The repair is not really interesting (he just swapped the motherboard) but he used an ultrasonic cleaner to clean the GBC's shell and buttons. If you look at 1:38 you can see the A/B buttons look good, but at 10:24 some white came out of them.

Have you noticed the same yourself or was it not visible before the clean?
Also he said he won't clean the back shell because of the sticker, is it possible for the the ultrasonic cleaner to also remove or damage it?

 

When using a light enough setting, ultrasonic cleaners do well with plastic. I've seen guys dump carbs with bulbs still attached sometimes in an ultrasonic cleaner to de-gunk them, and a lot of the time, they have plastic inner parts or casings.

 

two things
buy one with a sweep function (the do just flip between two oscillations)
most china ultrasonic cleaners are over rated in power