2018 HomePod making erratic noises despite rebooting

This is the OG HomePod model, now discontinued. There’s one method to get rid of strange noises with a hard reset started by unplugging for over 24 hrs first. Then plug back in and proceed as per instructions below

1. Unplug HomePod or unplug the power adapter for HomePod mini, wait 10 seconds, then plug HomePod back in.
2. Wait 10 seconds, then touch and hold your finger to the top of HomePod.
3. The white spinning light will turn red. Keep your finger down. 
4. Siri will say that your HomePod is about to reset. When you hear three beeps, you can lift your finger.

After you reset HomePod, you can set up HomePod again

Reset HomePod or HomePod mini - Apple Support

*Up to you if you want to try it but be aware this model can be hard to set up again and sometimes doesn’t react well to a reset and may stop responding. Or it may be completely fine.