Curious I’ve not see that before. There is a non-blocking reconnect every 5 seconds but that shouldn’t hold anything else up. If I get some time I will try to reproduce this on my hardware (I’m not using Blynk though). Beyond that you could try changing the following to increase the retry interval:
From:
if (now – mqttLastReconnectAttempt > 5000)
To:
if (now – mqttLastReconnectAttempt > 30000)