The ST-Link is a popular debugger on eBay/AliExpress, sold to be used with, for example the famous Blue Pill board. The debuggers sold on eBay/AliExpress are not official ST products. In stead, they are based on schematics published by ST, such as the Discovery and Nucleo series of development/evaluation boards.
There are many variants available. Pay attention to the pinout, as there are some different layouts out there. It has even occurred that the pinout printed on the aluminium case didn’t match with the actual pinout used by the board.