Not all USB microphones develop hissing/white noise sounds when plugged into a USB hub, but it’s generally true that with headsets, the microphone isn’t exactly what you’d call ‘premium’ quality. The reason for this is because more expensive USB microphones do have built-in physical filters to cut noise like that out, while on headsets the mic is left filter-less for the most part save for a mic sock which doesn’t help concerning white noise.

Are there hubs you can plug USB mics into that don’t produce white noise?

Maybe. More often than not a smaller 4-port powered hub will not produce white noise in a USB mic, but this is not guaranteed. Also, sometimes it works when you plug a USB headset w/mic in a slot away from other slots in use. This also isn’t guaranteed either, but it may work.

When in doubt (or if you’ve tried everything else), plug your USB headset w/mic into a USB port directly on the PC and not into a USB hub, and any white noise should go away immediately.