It depends! Is the feedback related to a product, to a team, or to a person?
For a product: I will always give open feedback because it is the easiest way for someone else to understand what I am looking for as a client or user.
For teams: during 1:1 sessions, it is the best time to give open feedback. If the leadership is transparent enough, the lead, manager, or director will know how to transfer it to the team.
3- For persons: just if the person is asking me directly for my opinion I will give open feedback or if I am a manager talking with a member of my team.