The vast majority of black players are not labelled with having a bad attitude (or gangsta whatever that means) because, their actions indicate that they have a good attitude! (There are quite a few black players in our team that are praised for their attitude) No matter what race you are, brandishing your wealth in public and making music videos will rub some people the wrong way.
Have a look at Valencia's public profile, it's quite boring like most professionals that are very dedicated to their craft. The same can be said for Zlatan. Sanchez pretty much posts about his family, dogs and football. Pogba on the other hand seems to have so much non football stuff in there.
Remember when we had that hashtag dedicated to Pogba against Liverpool at OT, and he proceeded to have an absolute stinker? Of course he could have had a blinder that game as well, but it's reasonable to say that his game was affected.
If anything, Pogba needs a PR manager. Posting about haircuts and promo vids after a loss or run of poor form is not good PR. If he replaced those with training pictures or not posting at all then his public image would be a lot better.