Open the following page:
It does not load correctly. The flow-ui-load-overlay div tag is preventing users from editing.
With all gadgets disabled from preferences, my Firefox 63.0b12 (64-bit) console is showing the following messages: P7652
I think the issue is related to the fact that mw.config.get( 'wgPageName' ) is returning null on that page.
I can't tell when exactly the issue has started, but the last edit on the page has been on 2018-06-30, for a page that has been having tens of edits per month, so my guess is sometime around that point.