It is the edge of the paint colored film installed at factory. OP you can try spraying some APC or Isopropyl alcohol diluted 50/50 along the wax build up. Let it dwell for a bit and soften the wax and then gently wipe with a microfiber. Wipe along and away from the edge, not against it.
Be sure to re apply wax or sealant in the area that you may have inadvertently removed it from, but stay clear of the edge of the film. Sometimes I put down detailiers tape to avoide the edges when waxing.