Correct your friend in private. Protect them in public. Both are loyalty.

Honesty and defense look like opposites until you notice they are aimed at different rooms. Telling someone a hard truth where only they can hear keeps their dignity intact while the information still lands. Backing them where others can hear means they never wonder whose side you are on. Do only one of the two and you are either a flatterer or a problem.

If you have something critical to say to a friend, find a moment with nobody else in it. When someone goes at them in a group, say something. The order matters more than the exact words.