Per:
https://github.com/discourse/discourse/commit/dc703adad77caf63a5a93de55798d2c3590fd1fc
And
https://github.com/discourse/discourse/commit/24ef4f7b2bbbe233999977615df85d43218080fa
We removed disable_jump_reply setting which was a fundamentally wrong and only partial broken solution to “allow me to jump to first unread in a topic”.
We added default_title_count_mode which allows admins to choose the default behavior for the count in the title (either contextual or notification count).
Users can select how the count in the title works per:
The count will be “unseen notification” by default, but they can switch it to “unseen page content” if they wish.
We decided to keep Show new / updated topic count on browser icon cause many sites amended the default here and the feature is widely used.