An unhappy discovery after we placed a HomePod on an oiled butcher-block countertop and later on a wooden side table was that it left a defined white ring in the surface. Other reviewers and owners (such as Pocket-lint, and folks on Twitter) have reported the same issue, which an Apple representative has confirmed. Apple says “the marks can improve over several days after the speaker is removed from the wood surface,” and if they don’t fade on their own, you can basically just go refinish the furniture—the exact advice Apple gave in an email to Wirecutter was to “try cleaning the surface with the manufacturer’s suggested oiling method.”
I didn’t have my HomePod placed on an oiled wood surface, so I never noticed this. Still, it doesn’t seem like this is something you would want to have happen when placing a speaker in your home.