In the Amazon Music app there is a setting called "Loudness Normalisation". Disabling this fixed the problem. I suspect the default value was inadvertently changed during a software update.
Thank you for the follow-up post, I appreciate you coming back with your solution! This is sure to help other users who run into the same normalization issues with their Amazon Music app. In the meantime, do you have any other questions or concerns that we can address? If so, please let me know!
