Gohan has many periods, and there are different martial arts costumes in different periods. Now let's take stock of the belt color of Gohan's samurai suit:

Childhood (hell training suit for piccolo training): blue

Childhood (hell costume): red

Adolescence (shouldered inferno costume+inferno costume): blue/red

Future period (Mizi Daofu): blue

Puberty (no words): blue

Youth (blue uniform): red

Youth (Super Isaiah Superman costume): black

Youth (the potential of old Kaiōshin is open):

Finally, the growth chart of Gohan is attached.