the Kesu brand external HDD was purchased on aliexpress, inside the case there is a WD HDD I ran this Victoria Quick test before writing the files to the HDD. Does it provide any parameters that the HDD really has 1TB and doesn't have badblocks and errors?
Try "Hard Disk Sentinel" or "Crystal Disk Info" both the software will show size of the disk (HDD, SSD or NVME) as well as bad sectors if there is any.
