The problem is that genuine 23-pin D-Types are rarer than Hen's teeth. So the only (affordable) means by which these cables can be created and sold is to cut down 25-way connectors.
Now, obviously, cutting a 25-way down to a 23-way is not going to make it look like it just came off a production line.
But there's no need to worry about connecting this to your AMIGA. The trace of copper that you see looks like it is the remains of one of the discarded pins of the 25-way connector. So it's not connected to anything.
If you plug this in it's not going to damage your AMIGA.