Well, you didn’t really give us much to guess on… what you are trying to do, how you are hooking it all up… what your code looks like, and so on.
But you can start by Googling and learning how an ESP8266 governs it’s GPIO pins on boot… Hint, not like an Arduino 
Some boot HIGH, others LOW… with a few rapidly toggling between both before settling.
NOTE, this is NOT a Blynk specific issue, rather, it is normal ESP8266 behavior (and documented many times already in this forum)… Please remember to search first ask next, as recommended in the Welcome Topic.
But, like with Arduino, GPIO pin states can be can be modified at boot by code with pinMode() commands in your sketch.