- A user with flow-enabled User talk page creates a page.
- Reviewer clicks 'Mark for deletion' via Special:NewPagesFeed -> Curation toolbar
- "Failed to notify author on talk page" is displayed, but the action is correctly done and a proper Notification is recieved.
The problem with "Failed to notify author on talk page" is that the Curation toolbar gives no indication that the 'Mark for deletion' action is, in fact, completed. It is still displayed with open 'Mark for deletion' options.