Curious if anyone can explain the dip in the middle for triathlon? Or is it pure coincidence?

It might be different in other countries, but where I'm from (the Netherlands) pink is definitely associated with gayness. After the second world war, when gay men in concentration camps were forced to wear a pink triangle badge, the symbol and color were reclaimed as symbols for queer rights. And even though the rainbow flag is now a more well-known symbol, it is still quite common for LGBTQ+ spaces/events to signify their intended audience by calling themselves 'pink bars/parties/...'.