Welcome to the SeeMeCNC Community

So I was printing a set of parts, and... occasionally one ends up with a weird outside that lacking of a better word looks like rot. As far as I can tell it's random when it does occur, and it's occurring like 1 out of 4 times.

This to my eye, is over extrusion (the reverse of starvation) that builds upon the problem as the part goes getting worse and worse as there is less and less room for the extruded filament over build up from previous layers.

I think what's happening is you're retracting too much and the filament is partially jamming on the resume. That causes the filament to fail to extrude immediately, then as the partial jam clears the pressure equalizes and you get all the extra filament.
I can get exactly the same effect with PLA in an E3D Hotend, if I try and retract more than about 2mm of filament.
I don't get the same effect with other plastics.

It's ABS....lol... Now that you mentioned it though, I did turn retract down from 10 to 5. But everything seemed fine for many prints so I forgot about that change.

The weirdest part is it only happens on the very outer layer from what I can tell, it does fix itself after so many layers, and if it doesn't do it the parts end up looking great. I did use Kisslicer with my the applicable settings (.2 layer, .4 extrusion width, 1.73 mm filament, .86 flow adjust, 227C hotend (I can't break 231C atm because of a bad cartridge),and I probably should've have that in the opening post...). Thanks for the suggestions, I hadn't seen this variation specifically yet so I got stumped but I'll re-check those suggested items.