The separate Lessons page is being retired. Your lessons now live in My Library, alongside your pathways and tutors, and that is where new features are being added.
The page still works for now, and opening it shows the banner above. Nothing has been deleted or moved out of reach: everything the Lessons page listed is in My Library.
Where to go instead
Look for the Library group in the sidebar. Lessons, Pathways and Tutors are nested underneath it while they wind down.
What you gain by switching
My Library does everything the old page did, and adds folders so you can group work by term, class or topic, filters by type and date, and a trash you can restore from. Pathways and tutors sit in the same place, so you stop hopping between three pages.
See My Library: where your content lives to get started.