On February 1, 2019, Scryfall will be removing support for the 1v1 Commander and Brawl formats.
Maintaining format data is a nontrivial task for the Scryfall team, and we have come to this decision based on changes to WotC’s support for these formats. (Brawl, 1v1 Commander)
Scryfall API objects will lose the legalities[brawl] and legalities[1v1] properties on February 1, 2019.
If you have questions about this update, please don’t hesitate to contact us.