Today, 14-March, it was discovered that some contributors' edit saving flows are being severely disrupted.
More specifically, contributors using mobile Safari on iPhone are finding the "Save" button is both a) out of view and b) unable to be scrolled to, rendering saving an edit extremely difficult. [1]
Current status: this bug is actively being worked on. The progress of which you can follow in the Phabricator ticket linked here and above.
1. Technically, the "Save" button can be accessed, and an edit saved, by "pinching to zoom out"