Why do I judge feedback by who gave it instead of what they said?

When criticism arrives, your first question is who said it. If it came from the wrong person, you let that cancel the message, even when the message was true. The messenger becomes the excuse to ignore the meaning. It feels like discernment, but often it is a way to dodge. A true thing does not become false because you dislike the person who said it. Some of the most accurate feedback comes from people you would never choose as advisors: a rival, a difficult colleague, someone with their own agenda. Their motives can be mixed and their point can still be correct. Try splitting the two apart. When feedback lands, set aside who delivered it and ask only, "Is any part of this true?" Deal with the truth first. You can consider the source later. Do not let a messenger you dislike rob you of a correction you needed.