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This is not the first time Facebook has been using the audio API to do background processes. A good proof is that when I am playing music over AirPods and open the Facebook app it often stops the music.

I deleted FB for now.
Mine does that when I had been playing a video or reel and didn’t mute the video again. When autoplay is active with sound on the Facebook app, it mutes whatever other audio you’re playing. That’s been the case for a while now. I just mute the videos and restart the external audio and all’s good.
 
Weird. I’m running the public beta of 16.1, so maybe that’s the difference, but I just checked, and the Facebook app has only used 3% of my usage in the last 24 hours. That’s pretty normal for me.
In my case it was showing as only 3% but the background process were very long hours. Weird thing is, battery is back to normal after deleting the app.
 
Yep, I noticed the background issue a few days ago (iOS 16.0.2) but it seems to have been fixed now.

Last 10 days: 2h 6m screen, 11h 40m background
Last 24 hours: 15m screen, 6m background (still the highest usage app on my phone, though!)
 
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