I was using the app quite regularly for a long time since my car didn't come with Sirius when I bought it. Then I started having issues, most of the same ones listed here. I use an iPhone and use CarPlay quite often when I'm on the road (45 minute commute to work one way) and the app would not work with CarPlay. With Apple Music or TuneIn I would turn the car off and leave the phone plugged in while checking mail or something briefly, and it would revert right back to what was playing when I started the engine again. Not with the Sirius App. It would stop, pause, then crash, then I'd have to reopen the app, reselect the channel, and whatever was playing before would be lost.
Nowadays I have my Apple Music subscription, and for Sirius-like content I have TuneIn Premium which is $7.99 a month, features all the sports available on Sirius with no bandwidth issues and home and away broadcasts. Also ESPN Radio, and other local ESPN radio stations all over the country if I'm so inclined. Also have live audio feeds of CNN, MSNBC and CNBC (FoxNews doesn't seem to want to play along but no big loss, Although FoxNews radio is there). And 100,000+ radio stations from around the world, plus Premium, Commercial Free music with expanded playlists, and no DJs (No Madison!!). Plus it has all the stuff that was removed from Sirius at some point. BBC Radio 1, C-SPAN Radio and others.
Not to mention, for some unknown reason, Sirius still refuses to work with the Homepod smart speakers from Apple. Pandora does work natively so I know it's a SiriusXM issue, maybe their app developers just don't know how. That would be my guess. Maybe walk over to the Pandora side and see how they do it. But again, no skin off my back.