- set user preference for "Add pages and files I edit to my watchlist". (via web not app) in this case was done as global preference.
- make an edit
- hit next to get to preview
- hit next to get to edit summary
if the page is already on user's watch list then form loads with "Watch this page" checked, if not then unchecked.
on desktop, with this preference set, when clicking the edit tab page always loads with watch this page checked by default.
2.7.50432-beta-2023-03-06