I drive 2023 M3 Competition (US model) and found something weird today. If you open the trunk, there are two cubby holes on the left and right side.
The left side hole came with the cargo net, but on the right side, the cargo net is entirely missing. See the attached pics.
If you see the following video, it appears that 2021 M3 Manual Shift model comes with cargo nets for both sides.
I'm curious if I need to ask the dealership about this. I wonder if other folks have the same configuration as mine.