He would be rewarded
Ibn Al-Mubaarak said:
“Whenever a man would see something from his brother that he dislikes, he would give him orders in private and forbid him in private.
Conversely, he would be rewarded for him screening his brother and also rewarded for forbidding evil.
As for today, whenever a man sees what he dislikes he angers his brother and unveils his screen.”
[Raudatul ‘Uqaalaa, p. 197]