Here's a way in which they can save 100% of the size: Stop stubbornly barring mobile clients from using the web interface. This is why I don't use Facebook Messenger at all.
Would be interesting to see how many seemingly harmless apps start to break, I would expect similar results to surfing the web with a JS blocker.
Isn't the screen off in nearly all of the legitimate uses of a microphone, ie. "I'm replicating the ux of a phone call in my chat app"?
I didn’t pull the trigger on canceling the account as from time to time I find news and event from pages that I follow, but there’s no way I’m installing an app that uses so many shady tactics.