It’s even more important to give it bluntly if the feedback is irrelevant. That way you’ve wasted less time.
Me: “we aren’t giving enough guidance to new hires” Leader: “it’s not a priority for us since we are freezing hiring”
Perfectly good interaction, where you didn’t waste time sneakily phrasing things you think you know better than the leader. And you learned some valuable info about the org priorities as a result.
If the feedback is irrelevant, you'll waste the least amount of time by not giving it at all. (I think that's slightly different from your scenario though, where you don't actually know if it's irrelevant.)
And how would you know if it is irrelevant? See prior comment.
Depends on the org and how information travels. Knowing tricks like this are the superpowers of people who move up quickly in large orgs and make things happen. You can sometimes do fine without knowing this, and going through the "official" route of the direct feedback loop. If you can figure it out elsewhere though, it'll usually build more trust with your superiors.