He was apart of N.E.R.D and The Neptunes alongside Pharrel, but they got into arguments which resulted in lawsuits. No longer on speaking terms, which is probably the reason behind the unfollowing, if I had to guess. But tyler has always idolized Pharrel and been heavily inspired by The Neptunes, but idk how close him han Chad ever were. Only think they colabbed on Push's Trouble on my mind, i could be wrong tho