What is this flashing blue icon next to the music?

Hi Gtlo,

It sounds like you're trying to find out more about the symbol you see, and I want to help.

That symbol in Control Center allows you to audio output:

Use and customize Control Center on your iPhone, iPad, and iPod touch - Apple Support

How to AirPlay audio - Apple Support

Let me know if that helps.

Thanks for using the Apple Support Communities.

AirPlay Icon. It's indicating that you are using bluetooth enabled devices, instead of relying on a wired connection.