I keep Smart Notifications on on my Fenix 5. I set up 1 / a couple of alarms.
If at the time of the alarm firing there's a "smart" notification showing, the alarm will just casually skip.
If while the alarm is ringing, a "smart" notification shows up, the alarm is permanently killed (unless I manually close the "smart" notification, in which case the alarm comes back alive).
This behaviour makes the alarms unreliable, hence completely useless.
Chances are that in the morning somebody will start being active online and unknowingly make me sleep in.
And it's so straight forward that alarms should have priority over everything, I don't care about my instagram like if a bloody alarm is ready to come up.
Software version is 12.50, but this has been happening for so long now.