The word "Cancel" always implies, that an action is not performed or that an already performed action is undone. See this screenshot:

The word "Cancel" in the upper left makes me believe, that any changes I made there won't be stored. In fact, the correct word here would be "Back" or even better, using the iOS back arrow that Apple uses in their interfaces:

bitwarden 1.11.1 (21) on iOS 11.0.3
The word "Cancel" always implies, that an action is not performed or that an already performed action is undone. See this screenshot:
The word "Cancel" in the upper left makes me believe, that any changes I made there won't be stored. In fact, the correct word here would be "Back" or even better, using the iOS back arrow that Apple uses in their interfaces:
bitwarden 1.11.1 (21) on iOS 11.0.3