This might be a very specific situation but it could probably also arise in other similar situations, where a single permanent has multiple triggered abilities firing at the same time.
In my case it was a commander game between me and two AI's on my local server (running build 2021-07-08 10:44).
Computer 2 attacks computer 3 with
Skyrider Patrol enchanted by
Steel of the Godhead while they also have
Noble Hierarch,
Angelic Benediction and
Angelic Exaltation, all of which trigger since
Skyrider Patrol attacks alone.
It is important that
Angelic Benediction has two triggered abilities, both triggering at the same time.
One of which targeting a Zombie Army token I control that is protected by
Kira, Great Glass-Spinner.
Now the following happens. The Zombie Army counters
Angelic Benediction, but it counters the wrong ability of
Angelic Benediction.
The Zombie Army does get tapped and Skyrider Patron does not get +1/+1.
9:13 PM, T19.DA: Computer 2 - Ability triggers:
Angelic Benediction [2db] - Whenever a creature you control attacks alone, you may tap target creature - targeting Zombie Army [c66]
9:13 PM, T19.DA: Tharkon - Ability triggers: Zombie Army [c66] - Whenever this creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability.
9:13 PM, T19.DA: Computer 2 - Ability triggers:
Angelic Benediction [2db] - exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
9:13 PM, T19.DA: Ability (exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)) of
Angelic Benediction [2db] is countered by Zombie Army [c66]
EDIT: The order the triggers belonging to Exalted Benediction are put on the stack matters. Kira's ability counters the topmost one on the stack regardless of which one it is supposed to counter.
https://github.com/magefree/mage/issues/8026