I have disabled Dolby Atmos in Amazon Music Unlimited but it still plays Dolby Atmos when using the Sonos app.
I am not sure if this is an issue with the Sonos app not honoring the Amazon settings or if the integration with Sonos is with the Amazon development team.
Either way, I would like to suggest that Sonos or Amazon exclude Dolby Atmos when it is not enabled in the Amazon music settings.
Thanks,
Wazza