Iv clicked a few screenshots to explain my issue.
When I clicked on Patan Devi in my watchlist (latest revision)
This diff screen appears, which is good. But when I click Patan Devi here
This appears instead of the article (Till one month ago it was ok). You can't save your edits after this screen anymore. There's annoying notice on the top of screen. Also see, that there's duplicacy of previous and next revision in 2nd and 3rd screenshot.
This is the url (now, 1 month ago url did not have any oldid in such flow)