They point out that they’re not alone in this discovery as other reviews of the speakers have also highlighted the issue. Apple has since come forward and acknowledged the problem, and has attributed this to the oils “diffusing between the silicone base and the table surface”. Apple claims that the stains will go away after several days if the speakers are removed, but if not they suggest wiping the surface of your furniture or clean it using the furniture’s suggested cleaning method.
According to Apple, this is not “unusual”. “It is not unusual for any speaker with a vibration-dampening silicone base to leave mild marks when placed on some wooden surfaces. The marks can be caused by oils diffusing between the silicone base and the table surface, and will often go away after several days when the speaker is removed from the wooden surface.”
That being said, this by no means impacts the quality of the speakers or its functionality, but it does limit where users get to choose to display it. Alternatively if you have no choice but to put it on a wooden surface, perhaps consider putting it on top of something, like a mat.