I am sure you have noticed that Nick Kyrgios wears two shirts – a compression shirt that’s tight fitting and a basketball jersey-type shirt over that. He is perhaps the only tennis player to do that.
Buy why? Until 2020, Kyrgios was wearing one shirt like other tennis players. It looks like he is now trying to be fashionable but also trying to go for the basketball look. The tight undershirt may also be too revealing, especially his imperfections, and an overshirt helps hide that.
Another fact to note is that he is sponsored by Nike. With two shirts, Nike gets an opportunity to market two shirts that have become popular because of Nick Kyrgios.
Nick Kyrgios has never been normal. He likes to stand out. His unique clothing is a way for him to be different from all other tennis players.