At least two rare variant Pokemon cards have mysteriously appeared in pre-release boxes for an upcoming expansion. PokeBeach, a popular Pokemon Trading Card Game news site, has reported that Cinderace staff promo cards were distributed in two Build & Battle boxes for the upcoming "Chilling Reign" expansion. PokeBeach has two verified reports - one from the UK and one from Kansas City - of the Cinderace promo card appearing in random boxes. The cards have two stamps on the artwork. The first is the standard prerelease promo stamp of Chilling Reign's logo on the right-hand side of the art. The other is a gold "STAFF" stamp on the left-hand side of the artwork.
Staff promos were cards distributed to volunteers who staff various Pokemon Trading Card prerelease tournaments and other Play! Pokemon events. These were popular promo cards distributed to volunteers for over a decade, but the Pokemon Company announced a "temporary pause" on Staff promos in 2020. The last Staff promo card sent out by The Pokemon Company was a Charizard promo card connected to the "Vivid Voltage" expansion that sells for hundreds of dollars on eBay.
The Pokemon Company hasn't announced anything about the Cinderace cards, so it's hard to tell if they meant to re-start the Staff promo card promotion now that stores are hosting prerelease tournaments or if this was some sort of production error. Clearly, The Pokemon Company didn't mean to just send out super-rare promo cards at random, so we're guessing this was some sort of miscommunication during the printing process.
The Chilling Reign expansion officially comes out this weekend and features Pokemon originally seen in the Crown Tundra area of Pokemon Sword and Shield's Galar region. The Pokemon Company has also announced "Evolving Skies" as its next expansion, which will bring back Dragon-type Pokemon cards and feature the Eevee evolutions in V cards and VMAX cards. The Pokemon Trading Card Game is also planning a new type of card - the V-UNION card, which is technically a Pokemon made up of four separate cards. V-UNION cards will be released in Japan later this year and should appear in the US and abroad soon after.