Good feedback focuses on the design.
Bad feedback focuses on the designer.

Good feedback helps the designer feel like they’ve had a light bulb moment.
Bad feedback makes the designer feel upset, anxious, or sad.

Good feedback comes from a place of generosity and kindness.
Bad feedback comes from a place of competition and pride.

Good feedback adheres to the type of feedback a designer is looking for.
Bad feedback tends to disregard it.

Good feedback is timely.
Bad feedback comes too late to be helpful.

Good feedback is contextual. Explaining the why behind your thoughts?
Bad feedback is, “Because I don’t like it”.

For managers and leaders. Good feedback communicates whether it’s a suggestion or a mandate.
Bad feedback leaves the designer guessing.

Finally, good feedback communicates prioritization. Is it high priority, medium priority, or low priority?
Bad feedback is just a big list of stuff, without any prioritization at all.