Week 17 was past the original launch of date of Beyond Light, which would have taken us into Season 12. The API is also subject to change before anything is reflected in-game.
The rotation probably didn’t change with the extension of the season. In any event, since the season was going to initially end well before that, what exactly are you mad about? It’s just a matter of semantics since it would have been available at the same time if it were season 12.