It seems Toriyama later regretted the way he developed Gohan from the Buu Saga onwards. This is very clear in the Dragon Ball Super: Super Hero movie, which finally gave Gohan the momentum he deserved ...

Goku is the only character in the series who has been able to unleash Ultra Instinct, but Gohan, Vegeta, Piccolo ... his SSJ transformations (except in the Other World Tournament, an anime filler arc) ...