Absolutely. If you own a bricked, boot-looping, or Chinese-variant Vivo Y66, flashing the global firmware is the most effective cure. It restores full Google functionality, fixes network issues, and brings back the smooth Funtouch experience.
: If firmware issues cause severe lag, a "Wipe Data" operation in recovery mode can restore the phone to factory settings, though it erases all personal data. vivo y66 global firmware
There are two different models of the Vivo Y66. Flashing the wrong firmware can hard-brick your device (turn it into an expensive paperweight). Absolutely