Well, I spooked myself.
Login to LibraryThing: apparently a member since 2016 with one book:
Typus Cosmographicus Universalis
It says I added it. I’m the only person on the site with that listed. It’s not even a book. It’s a world map from 1532.
Why did I add it? Jun 1, 2016
Stitching in time.
Oh, that has to be it.