Apple HomePod speaker is apparently leaving white ring marks on certain wood surfaces in normal use. However, Apple has responded to same by saying that it is usual for ‘vibration-dampening silicone’ to leave marks.
Apple in an updated support article has detailed on how to clean and take care of the HomePod and describes the issue as expected, but not a defect. The Apple response says “It is not unusual for any speaker with a vibration-dampening silicone base to leave mild marks when placed on some wooden surfaces” meaning that Apple is aware of this issue and there is also no fix coming since it is not a defect.
Apple says that the marks can be caused because of the oils diffusing between the silicone base and the table surface, but will often go away soon after several days when the speaker is removed from the wooden surface. Also, you can gently wipe the surface with a soft damp or dry cloth to remove the marks, If they persist. Apple also says that alternatively, you can place HomePod on a different surface.
While this is not a technical issue, Apple should have designed the HomePod so that it can be used on ordinary surfaces like wood tables and shelves without risking furniture damage.