In both GoodNotes 4 and 5 PDF "Back" (last viewed page) links are broken. At least in GoodNotes 4 you had the option of jumping up to the menu and selecting "Go Back" from the navigation menu.

PLEASE either fix "Last Viewed Page" links (preferred) or re-enable the Go Back menu item. Without that jumping to a to-do list to add an item and then getting back to your notes page is really cumbersome. With it that workflow is super easy.