I'm somewhat puzzled which settings I need to look at in PrusaSlicer to solve those thin slits between perimeters. I've dialed in the flowrate optimally for dimensional correctness and 245°C (PETG) works really well for both flow and overhangs.
At first I thought of extrusion width, but that also increases the distance between each line. Raising the flowrate closes them, but also makes the printed parts grow in each dimension outside if the intended size.
Where am I missing something? Which settings do I need to adjust to not screw up everything else?
EDIT: It's not just corners!
This comment is correct imo. Read / calibrate the pressure advance. I've had especially good luck with the adaptive pressure advance and highly recommend taking the time to calibrate it.
Its a little bit confusing to do, but once you get the hang of it and do a full calibration sweep it should fix all the 'corners have gaps' issues. (Also just any gap issues between line)
Pressure advance is going to impact any line where the head will be shortly changing directions. So though it typically is corners you can get it with any acceleration change of the print head.