Wizards changed the wording on the encyclopedia of magic page.

Yesterday it said

“Each copy of An Encyclopedia of Magic contains 26 individually wrapped foil Magic cards. Open them all at once or savor the anticipation. Either way, you'll find one card for each letter of the alphabet. Along the way, you might find foil cards”

Today it says

“Each copy of An Encyclopedia of Magic contains 26 individually wrapped Magic cards. Open them all at once or savor the anticipation. Either way, you'll find one card for each letter of the alphabet. Along the way, you might find foil cards—or, on rare occasion, Halo foil cards.”

https://magic.wizards.com/en/news/announcements/secret-lair-countdown-kit-an-encyclopedia-of-magic