hello guys, yes. apparently the guilty one here is the new and amazing feature called "WIFI assist" .. so just turn it off and you will save 10´s of gigabytes on cellular.
Apparently not. People are still experiencing the problem with wifi assist off. And of course the VAST majority of people that aren't experiencing any issues have wifi assist on (since its default is on).
This seems pretty typical IMO, after every iOS update there are a few people that experience high data usage. Unfortunately I don't know whats causing the problem.