Hi Amanda239_91,
This is on Macs, iPhones and HomePods.
I Have a music subscription and use it daily. I generally do not listen to music on my iPhone that is not downloaded, because the experience of streaming on the iPhone leaves a lot to be desired. My Computer is hard wired to the router and this is where I experience the issue most. (the vast majority of my listening is through the Mac)
so to answer your questions : mostly streaming on a Mac over a hard wired internet connection (gig speed) But occasionally on an iPhone that has downloaded the music, and on a HomePod which is connected through wifi. I never use cellular data on my iPhone for streaming music, as the device routinely blows through gigabytes of data consumption in the background despite being set to not use cellular, or update in the background at all.
in short: there's something wrong with the desktop version of Music.app. And I would really love it if it stopped canceling my groove right in the middle.