After the Super Bowl, the NFL pre-orders merchandise for both teams, but only the winning team's gear is sold in the U.S. The losing team's merchandise is donated to communities in need outside of the country through partnerships with organizations like Good360. This process ensures that the losing team's gear doesn't end up in the hands of resellers or collectors who could profit from it. In addition to merchandise, the NFL also prepares confetti in both teams' colors for the post-game celebration, with the losing team's confetti being recycled after the game.
Source: https://people.com/what-happens-to-losing-team-merch-after-the-super-bowl-8786961