It was a leak on the PTR with the achievements. There’s an achievement to finish the brawl with six heroes and their icons are on the achievement, clearly showing new skins.
You can see them here. Sombra looks like she has a cut on her cheek? Seems like a stitch which might imply she’s the bride.
I’m just disappointed that Hanzo likely isn’t getting a Halloween legendary for the third year in a row and will be the only brawl hero without one. On top of that, three years in a row no summer skin for him either. I don’t understand why can’t they distribute skins evenly instead of giving some heroes several for the same event while others receive nothing.
Maybe these six skins aren’t the only new legendary skins, but seeing as what happened with summer games, I won’t hold my breath.