If you click the notification, you are not taken to the Google Play Store or your phone’s genuine Settings menu. Instead, you are redirected to a third-party download page hosting a file named update_8259.apk or SecurityPatch8259.apk .

Look for "YT5760B" or similar identifiers in your build number, as firmware is highly specific to the manufacturer's board configuration. Methods for Updating the 8259 Firmware 1. Online (OTA) Update