He is an embarrassment to his parents, his brother, and the Chiefs. His off field antics may be affecting his brother's focus. It is a game of degrees and inches and it doesn't take much to hurt the winning psychology of even the best athletes. Anyone that's competed at high levels has experienced the challenges of maintaining a winning psychology.
Not alone here:
"Whether you agree that Patrick Mahomes ranks among the best of the best in the NFL or not, most people can agree that they just can’t stand his younger brother."