Theory: This unreleased common skin will be released tomorrow as part of the 1 Year Anniversary Challenges. It makes sense as tomorrow is the last day of Season 5 and it's only
All unreleased Fortnite cosmetics as of June 1st, 2019 - Fortnite INTEL
Bets on which unreleased skin/s will be in the last shop of the season tomorrow : r/FortNiteBR