I have an Android phone, so my Spotify is streaming through Android Auto. I have not noticed any cutouts while listening to Spotify via Android Auto, only while listening to XM radio. I had just assumed that the satellite antenna was not as robust as our previous GM trucks, but it sounds like it may be a different problem.
On a similar note, driving back from Florida after New Years, my daughter commandeered the radio and she streamed her music on the head unit via CarPlay, and I did not notice any cutouts during that 11 hour drive.
To be fair, all of the ladies in my family are non-stop talkers, so the only time I really ever notice cutouts is when I am driving by myself listening to XM radio.