I didn’t say that your mobile data provider would be blocking access to the Blynk severs, what I said was:
There is a difference.
Maybe reading this will explain more:
I’m unclear about why your project worked initially but not now, but I guess there are a wide variety of possibilities including changes made by your ISP, a different cell tower with different configuration etc.
I assume that you e restarted your phone?
Maybe running something like WireShark may provide some insight.