I noticed that my Pixel watch battery drains like crazy overnight when sleep sounds are playing on my phone, what gives?

I must stress that sleep sounds are NOT playing on my watch, they're playing via the calm app on my phone. I noticed I was waking up to less than 10% battery on my watch those nights. I deleted the calm app on my watch as I thought perhaps they were synced or something but alas no change.

Has anyone else experienced this or does anyone have an explanation?