I don’t think stroke-width is used in any part of the calculations the uses to create the cut. You could set your stroke-width to 50mm and it wouldn’t care.
Yes, you are correct stroke width doesn’t matter for the GF.
But our discussion is at the pre-GF stage, this is an issue with the design even before it is cut on the GF. The way OPs design is cut in the image, the path cut out is a design feature. OP likely didn’t pay attention to the default stroke width in Inkscape, lets say it is x mm. So when OP converts the design to cut (stroke-to-path menu) the path width becomes x mm. uploading this svg would result in a material thickness of (x-kerf) mm irrespective of what the assigned stroke width (e.g., 50mm) is in the uploaded file.
After re-reading my initial response I realize that my response referred to SVG design not to GF cutting per se, sorry for the confusion.