Question about Anarchy Battle (Open) Matchmaking

So I just recently got to S rank, and my girlfriend is now saying she doesn't want to play with me because I'm such a high level 😅

How does matchmaking work for Splatoon 3? Will they average our levels for who to place us with? Or will it be based off of mine since I'm the highest level? Or possibly even just based off of who opened the room? I honestly have no idea, so any info is appreciated!