Comment by nextos

Some people, including legal experts, claim it could have been intentional: https://www.legal.io/articles/5691258/Novo-Nordisk-Lets-Cana....

I was surprised Science didn't discuss this option. However, reader comments in Science do comment on this possibility.

The idea is that letting the patent lapse would avoid getting regulated by the Patented Medicine Prices Review Board.

I know several people working at NN, and it's quite chaotic and political, so I wouldn't rule out an internal oversight.