alsa-project/alsa-utils issue #255 was edited from Porkepix:
When in an environment not intercepting those keys (usually managed by your compositor/window manager), upon receiving some keycodes such as volume up or down, alsamixer is exiting and writing the UTF-8 keycode inside the terminal while it shouldn't.
Examples: Mute key > 440u Volume down key > 438u Volume up key > 439u
Curiously enough, the microphone mute one doesn't do anything.
These should at the very least not exit alsamixer. A bonus would be, when they're not intercepted, to actually use them to apply mutes and volumes up/down.
EDIT: Terminal here is Alacritty as that behavior might change with others eg. if they're not sending any key codes over to what's running.
Issue URL : https://github.com/alsa-project/alsa-utils/issues/255 Repository URL: https://github.com/alsa-project/alsa-utils