Observer Blind Spot Bias
It's when someone who's supposed to be neutral acts like a fanboy who only sees their team's mistakes and ignores the other team’s.
The food critic said the restaurant was the best, even though the waiter spilled soup on his shirt.
The movie reviewer gave it 5 stars, even though the plot was worse than a bad bedtime story.
The teacher gave the kid an A, even though he cheated on the test.