Since a few days ago, my WH-1000-XM3 have been playing notification sound while i listen to music if they come through, even though I usually have my phone on silent. This issue continues even after the headphones are disconnected, and the notification sounds will continue to play on the phone despite silent mode or do not disturb. It seems like the headphone makes the phone treat notification sounds under media sounds rather than ringtone sounds as the volume of these notification sounds are dependent on the media volume, hence why putting the phone on silent does not work (But muting media sounds does).

This is not an issue with my phone as I had tested it out with 2 phones, and this issue only pops up after these headphones are connected for the first time following a reboot. This issue then persists afterwards until the phone is reboot again.