wasn’t my idea… saw that on a youtube video once, where they balanced a 1.35m diameter carbon prop that way.
after posting the pics, I damaged the same prop on the other side at about the same spot.
I know now where it comes from:
It must have been the netting, more precisely one of the knots in the last row right were the tension string is.
I thought I pulled it really tight, but it was still sort of close to the prop. In preparation of my flight today I connected the netting a couple of inches lower to the frame, and that allowed the netting to be secured a bit better behind the two lower arms.
I will have to make sure in the future to always pay really good attention of tightening the net and where I connect the tensioning strings to the frame!