Official Over-The-Air (OTA) updates are released by ZTE to address specific issues. If your phone is suffering from random reboots, camera focus issues, or Bluetooth connectivity drops, a firmware update often contains the necessary patches to resolve these glitches.
For the ZTE Blade A7 (2019), the firmware is essentially the "brains" of the phone. Updating or changing this software can fix bugs, improve battery life, patch security vulnerabilities, or completely revamp the user interface. Zte Blade A7 2019 Firmware