You should know that when a message you convey to another person is not understood by him, at least one of the following things is true: what you have said is not true, or you have conveyed it without kindness.Leo Tolstoy
The problem of course is that different people need different types of kindness. And you can’t just ask. Asking someone how they like to receive feedback is useless. Everyone says “just be honest” or “tell me directly” or whatever.
Saying it with kindness requires truly knowing the person.