Hey, Buddy – sorry for the delay in seeing this post. If I had to guess, it looks to me to be an EXTRUSION WIDTH parameter. I’m not familiar with your slicer, but that is what the parameter is labeled for Simplify3D. Sometimes there is an “automatic” setting and a “manual”, switch to manual and adjust the setting to something less than the nozzle diameter, say .38. The issue here is the wall is drawn at .4, but the wall is actually less than that on a radius – if that makes sense to you.
Thanks for the picture – that showed me immediately what it is. You should also see this in the visual in your slicer – but again, unfamiliar with yours.