Maybe you are using ESP8266 2.3.0 core for Arduino IDE? Because if you are, that would explain it. Details here:
https://community.blynk.cc/t/wpa2-compromised-upgrade-all-hardware/18353/15
If not, then try this, maybe it will work. But I still think it’s not code related.
Add:
char server[] = "blynk-cloud.com";
Replace this:
Blynk.begin(auth, ssid, pass);
with this:
Blynk.begin(auth, ssid, pass, server, 8442);
What kind of power supply are you using for NodeMCU?