Please read the welcome message and format your pasted code:
You have a void loop() in your BLYNK_WRITE(V3) which is probably one of your problems.
When putting this in your main loop the pin is read many thousands of times each second:
pirValue=analogRead(A1);
piezoPir=pirValue;
Personally, I find no reason for such a high reading frequency and in a small sketch it might not even be a problem combined with Blynk. But Blynk favors the use of Timers to keep the main loop as clean as possible. If you search the forum you’ll find some examples of how others have implemented the use of PIR’s.
Good luck!