I was wondering the same thing, & kinda thought maybe it was to keep the look of the main character consistent thruout, so he's recognizable. Commenters on the original post said it's maybe for marketing purposes, which I agree with. They also said the suspected entrance to the DLC is the gold stargazer in the ch 5 graveyard, so maybe the DLC takes place before his hair turns grey? But then what does that mean for the plot & how much humanity P has? Is he going back into the past with the knowledge that his dad Gep is the one who started the puppet frenzy & is like evil, or will he still be a good obedient son? Will we be going far back enough for P and Carlo to coexist? (I doubt it tbh but it would be cool (also I'm not super clear on the timeline of the game, I haven't got all the endings yet)) And omg what if P meets Gep in the past??
Either way I think he looks so pretty in the DLC trailers teehee can't wait to draw him soon
So are there theories as to why P doesn't have grey hair in the dlc promos??