However when the feature was launched, there was a brief moment of concern that WiFi Assist might be too sensitive and that it could end up consuming more data than users would like. Now if you were worried about that, fret not because Apple has since clarified the issue with a support document on its website.
According to Apple, they note that WiFi Assist could lead to a small percentage increase in your data usage, but nothing worth being alarmed over. They also point out that WiFi Assist will not activate if you are data roaming, so bill shock should not be an issue for you. It also only works with apps running in the foreground, basically meaning the app you are using right now.
So if you’re worried about apps like Waze, Google Maps, Facebook, and etc. running in the background and eating up your cellular data when WiFi Assist is on, don’t. Last but not least, WiFi Assist will not work with some third-party apps that stream audio or video or download email attachments. Hopefully all of this helps clear up the doubts you have about the feature.