A few things. Pretty sure there are separate settings in Studio for the actual topmost layer and other, intermediate top layers. Have you checked that those both are set the same? And maybe something like ironing could help if you want a smoother finish?
And there can be circumstances that can put you close enough to having print issues that they start to appear just on parts of the print and not all of it. Especially with open printers, air currents can cool parts of a print, or humidity or water content in the filament can cause issues on tougher parts of the print. If things are borderline, little things can seem to have outsized effects.