You’re correct! I need to re-visit that.
Better to use the function I linked to earlier.
You need to use a sketch which has no Blynk code in it. Once the sketch has connected to WiFi and your MQTT server, you then subscribe to the topic that you’ll use to send commands to control the relay.
When a message arrives on that topic you’ll then work-out what the value of the message was (I guess you’ll use 0/1, but it could be On/Off, Apple/Banana depending on your preference).
You’ll then trigger a digitalWrite to control your relay pin.
The “Turn On/Off…” topic I linked to has some example code (which isn’t mine, so I can’t vouch for it).
This is a simplified version of my regular code:
Pete.