Welcome to the forum!
I don't actually have any kind of cutter, but I've been trying to keep up a little bit, so I can help new users. When I use gcode tools to generate cuttings paths, my gcode doesn't have any brackets in it.
Can you share exactly which extensions you're using, the steps you're taking, the various (or at lease relevant) settings, and maybe even the SVG and NGC files. Mine are attached for comparison.
Since we've seen this problem since version 0.92, I'm suspecting you might not have your Display Units and Scale settings configured properly. (I'm guessing maybe the info in the brackets is attempting to convert the scale??) So if you could also share that info - both of those are on Document Properties > Page tab. (note the Display Units is at the very top, but unfortunately often confused with the page size units about halfway down the page, which might need to be fixed as well, but probably wouldn't affect the output)
Let's see, you already mentioned Inkscape version, so if you could also tell us your operating system, then we should have just about everything we need