Yes, a bad seam can be caused by the quality of the sewing machine, the quality of the mesh, and, importantly, the quality of the thread. Often times, bad threads can be the cause of skipped stitches. In our workshop we only use Gutermann threads, also good threads of Madera, Amann Mattel brands. When we tried to switch to cheaper thread, we immediately noticed a significant decline in the quality of the applique.

I prefer 2x3 variant.

In order for the seam not to tighten the fabric, it is necessary to stretch the fabric a little while making the seam, as if by creating a slight twist on the machine to pull the fabric.