I was trying the new screen setup in Family Search but I couldn't find the "To Do List"
The To-do List has been added to the new homepage on FamilySearch! Find it on the bottom of the right-hand column. (On my mobile, it shows up as a different tab across the top.)
Also see https://community.familysearch.org/en/discussion/126457/keep-to-do-list-plz.