Why did trunk's ssj hair style change at the end of the cell saga

Future Trunks Long Hair (Base - SSJ - USSJ - USSJ3) Dragonball

When I was 12 I wanted to be Trunks. That was my bowl cut faze

Toriyama's art style changing over time with SSJ • Kanzenshuu

Which design do you like more? Dbz for me but I like supers blue

Super Saiyan Rage, Dragon Ball Wiki

Super Saiyan, Dragon Ball Universe Wiki

Every Important Dragon Ball Transformation, Power-Up, and Fusion

S.H.Figuarts SUPER SAIYAN TRUNKS -INFINITE LATENT SUPER POWER

If Vegeta said a Saiyan's hair never changes then why is his hair different in GT, Trunk's hair is different from the Cell Saga to Goku Black Saga, And Gohan was able