My CABLE STOPPED WORKING (Lightning to USB, 1m )

I’ve been charging my phone with a cable and power bank for a year and never had a problem with it. Last time when I tried to charge my phone again they cable stops working (I’ve checked power bank and it was definitely the cable which didn’t work).

The cable itself doesn’t have a visual defect or breakage. Only on the photo you can see that it has some black dots on the top of it.

Could it be the reason why it doesn’t work and what those black things on the top of the cable could mean?