u/Alive-Detective-4871

Hi, I have an Anycubic Kobra S1 Combo that is only 2 weeks old. I calibrated flow, temperature and Pressure Advance, reduced print speeds and dried the filament, but the problem is still exactly the same. The gold heart was printed before calibration. The blue heart was printed after all calibrations and settings changes. Vertical walls are smooth, but curved top surfaces are always rough like in the photos. Has anyone had this problem? Is this more likely a slicer setting, cooling issue or a hardware problem? Thanks!