Stop Windows from starting YouTube or Spotify in background when mic is used

[runtothehills]

I'm getting really frustrated that every time I wish to use my mic through my Bluetooth headset, when going into a meeting or leaving a voice note on Teams or Signal, YouTube or Spotify decide to turn on in the background and compete for my ears.

I get that the codec needs to change, but why do these background apps start to run when the codec changes?

How do I stop this from happening?