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.