PETG Top Layer Issue

[airscapes]

Make sure Minimum infill length is set to .01, ABS and PETG extrusion multiplier may be slightly different if you dud not calibrate it. What is your infill Outline over lap.. I typically use 14 o15%, PETG should have NO fan. Only time I have found fan needed is making very small tall parts otherwise 0 fan just like ABS
Try rectilinear for your infill pattern. nozzle size? Looks almost like what you get when the nozzle is too larger for the model
Sometimes you get better results with small items when you use only one perimeter, S3D will then fill the gap with single extrude, assuming you have single extrude fill turned on.
Also if that part is as small as I think.. you may want to slow it down and also increase the layer height a bit..