In case anyone is interested in the major changes in 2.0.x:
I love that this happens to larger libraries now. It doesn't need to be 100% complete, but it will still improve many devs' lives. I hope it will become the default for new projects and major updates.
He and his kind are in a different reality
I couldn't find a way to close the top banner. So I clicked around and found out this page had a bug. In the bottom right corner there is button to select the version of flask.
1. click v2.0.x, works fine
2. click v1.1.x, 404 page not found
3. click v2.0.x again, 404 page not found