It’s a reworked body model that looks skinnier than the default one, and it’s used with a particular texture that is created by converting PES 2018 to 2021 kits into textures usable in PES 6.Also another question to @*aLe : what's the "number 33" stuff you mention?
It has several advantages over the default model (the biggest of which is that the collar geometry is way more accurate than it used to be back in the day), but it does look too much different from the original one to me.
It’s been converted to PES 5 too, see here for more details:
https://evoweb.uk/threads/new-player-3d-models-for-we9-pes5-we9le.83803/