On the alarm’s timeline. It shows Notified with the number of recipients and channels, “Notification held back” when the throttle kept one back, and Muted when nobody was told.
The notification log only has attempts that were made (sent, failed or pending per recipient and channel). Something held back before it was attempted (by a preference, quiet hours, the repeat window or a mute) never got that far, so it is not in the log; those decisions show on the alarm timeline instead.