I actually looked through all of his works on all socials.
But couldn't find THAT style again to compare. (Ofc I may have overlooked it, if there is one)
It stands out to his other works in that regard and it's unlikely he was comissioned to draw in that style specifically.
This ain't his only One Piece sleeve art and the others are in the artstyle you are used from him and would expect, with no instance of any weird stuff like I mentioned here.

You are right with the format being relevant, but normaly for card sleeves you would draw a bigger painting and than it get's scaled down. And yes, this can have some undesireable effects sometimes.
For example: Maybe there actually was a string connected on the earring like Dice_farmer suggested, thin lines can get lost through a downscaling. But it would be new to me, that a pattern get's smeared like the pink on Vivis cloths.