When attempting to edit a page which is protected using the [[ https://www.mediawiki.org/wiki/Project:Protected_titles#Method_3:_Cascading_protection | cascading protection ]] mechanism, the MobileFrontEnd workflow goes too far before stopping.
Example, this page is protected and looks protected using the Vector skin, but appears unprotected on mobile. (Load not-logged-in to demonstrate)
DESKTOP: https://test.wikipedia.org/wiki/Template:Something_to_cascade
MFE: https://test.m.wikipedia.org/wiki/Template:Something_to_cascade
It allows the user to start editing, collects their edit, confirms it, asks for a summary, then finally fails with an ungraceful: "Error, edit not saved." leading the editor with only the option to abandon their change. The editor never should have got that far, the page should let them know it is protected and stop immediately.