When a page is protected, on Minerva, there is no way to view the source of the article. A toast is shown telling the user it is protected, with no way to view the article wikitext. Sometimes the source is important (for example copying and pasting the content into a draft/user space).
e.g. visit https://en.m.wikipedia.beta.wmflabs.org/wiki/Selenium_protected_test_2 in an incognito window and try to view the source of that article.
Constrast this with https://en.m.wikipedia.beta.wmflabs.org/wiki/Selenium_protected_test_2?action=edit
Original bug report
I tried clicking the locked pencil multiple times, but it did not work.
Surprisingly, it works on https://en.m.wikipedia.org/w/index.php?title=Module:Location_map
We could show a drawer similar to the drawer we show for blocked users; the one we show for clicking a red link; and the one to prompt users to login who click the watchstar.
The drawer could provide the explanation that the page is protected but offer an option to "view source" that opens the existing editor.
We'd probably need to make some updates to the logic for the editor, to allow it to operate in read only mode.
Also related: T150189, where we also added a link to a toast message