You can replicate the issue by setting an alarm, when the alarm goes on, turn the volume down to zero, the result is you're going to miss this alarm and the following until you turn the volume up.On my Pixel 2 XL, if I press and hold the Vol Down button, the Ringtone volume goes all the way down to Vibrate, but then I have to release the button and then press again in order to get to Do Not Disturb. But I haven't tried this when an Alarm is ringing -- does this only happen for you with Alarms?
I'm not sure, I'm totally unconscious whatever that shuts it off without me looking seems to be preferredWhen the alarm goes off, why not just tap the Dismiss or Snooze button (in the notification), or if you're on the lockscreen, swipe to the left or right to accomplish the same thing?
Just found an option to use the volume rockers for snooze instead of volume.So reading this thread, it seems like there's no bug at all and everything is working as intended. The volume button controls the volume of whatever is in the foreground. So if you press the volume down when an alarm is ringing, then you're controlling alarm volume to zero. Since you set it to zero, then it would be working perfectly when the next alarm does not sound at all because alarm volume is zero.
It's not an Android problem since it's working exactly as it was designed to work.
My suggestion is put the phone somewhere where you have to stand up to turn the alarm off.