Check your USB cable, try a different USB port (preferably USB 2.0), and reinstall the Qualcomm/Vivo USB drivers.
Global Firmware: Complete Guide to Flashing, Features, and Benefits The vivo y75a global firmware
Click the green arrow button at the top of the interface. The tool is now waiting for the device connection. Turn off your Vivo Y75a completely. Check your USB cable, try a different USB