That's a new made rail. I build such rails some years ago and will make some this year again.
I made them for the GSG-STG44 in .22lr, but they fit the originals as well.
The rail can be glued on the receiver with a good epoxy. This works well and is removable with a little heat and acetone.
@Absolut
You are right, it is a shame. But where to get an original rail when your eyes get older?