I expect it is a headwind requirement coupled with your altitude and how close to the start of the turn you are. Possible something along the lines of must be above 3000', within 3 miles of the turn and groundspeed not above 210kts or something similar before they can remove the 220kts restriction. As previously posted some days they say once on track to x no speed restrictions and on other days about 2 miles to the turn the say no speed restrictions.