Ok so in the troubleshooting it says:
Blynk.virtualWrite is in the
void loop , it generates hundreds of “writes” per second
Here is an example of what may cause flood. DON’T DO THAT:
Blynk.virtualWrite(1, value); // This line sends hundreds of messages to Blynk server
And this is exactly what the code is. So what are the exceptions of the rule?