When the HomePod mini was released, it came with an included 20W USB-C charging brick which is used to power the speaker and when users got their hands on it, it was quick revealed that the 18W brick that came with the iPhone 11 Pro last year was not quite enough power for it. In doing so, the HomePod would glow red / orange on the top display, indicating an issue. This was the case for some 18W third party USB-C bricks too.
However with the latest update to the HomePod mini, with version 14.3, it now works with those adaptors which didn’t work beforehand. Some users are reporting that it also works with some Anker battery packs too.