Thread:Sannse/@comment-35777977-20200328192014/@comment-1038387-20200328210146

Yeah, that's the Source Editor. Strangely, when the UCP wikis were launched, there was a setting to disable the editor - which gave you the source screen. That was changed about a week later to just being able to pick between the two.

Though that source screen was not the source you're familiar with on Fandom, it was basically Wikipedia's version of the source UI. Now that I think of it, maybe they removed the option because they haven't implemented their own source for the UP yet?