To me it looks like isolated die polishing altered the width/height of the roof line. When the over polishing is to strong, the the devices/building gets thinner. Thus the affected area was affected by several clashes. When over polished, the fields and mid devices were weakened and now the narrowed lower part of the devices are making some areas looking smaller. Thus the wavy affect of the roof line. (Probably the EPU was also affected making the devices there weaker. A closer side by side of a normal coin and this one, the EPU would probably show the narrowing better.