The default settings for auto/calm have some background noise cancellation, while the default settings for bluetooth streaming have none. The aids will automatically switch to the bluetooth streaming a second or two before playing a notification ping from your phone, or when you visit a website that has streaming video (even if it doesn’t automatically play the audio). If you’re streaming something and hit pause, it will stay in the bluetooth mode for about 5 seconds before returning to auto. In those cases, you’ll hear the difference as an increased ‘hiss’ from background noise like an air conditioner or central heating when in bluetooth mode.
Your or your HCP can change the background noise settings for streaming in Target. That will also impact the audio being streamed, so I’d recommend changing only the ‘streaming speech’ mode, not the ‘streaming music’ mode.