Fairly sure Sanchez got a hell of a lot of shit when he was playing more regularly. Work rate especially being the main thing he got criticised for and then in general just having no influence or impact on any games as you'd expect like he did for Arsenal.
Pogba is just in the limelight more, plays every game, ambles around every game and attracts attention with the Instagram stuff, the shitty penalty run-ups, the hairstyles (not fussed about this one, personally), the choreographed celebrations. Not to mention the amount of money that was spent to bring him in. He's simply failed to deliver. Even if he is top goalscorer/top assist-maker. Is it good to an extent that he's got those? Yes. Has he arguably still under-performed? Yes. Is it unfair to point out he could still do better and focus on football as opposed to all the celebrity-esque lifestyle he appears to give more attention to? No.
To say it's racist that he's got headlines about him is way off the mark.
The real racist shit that goes on is all the bollocks Sterling has/had written about him by the Daily Mail and that was correctly called out in my opinion.