Wizards of the Coast (WotC) will be reducing the amount of packaging used on a majority of Secret Lair drops starting with the April Superdrop.
Future Secret Lair drops will feature a smaller, envelope-like package instead of bulky boxes to create less waste and make distribution more sustainable. Check out the packaging below.
The black box packaging, seen below, will still be used for The Astrology Lands series, most philanthropic drops (Extra Life), and most cobranded drops (Street Fighter).
Read the original announcement from WotC.