While I try to give them a benefit of a doubt, there does seems to be something nefarious going on. First day, purple, second day red, third is green, now pink. Will blue be the winner tomorrow? My guess is yes and reason to believe the thing is rigged.
Reddit started a push to have every color get two wins. And while it seems unlikely that one small subreddit could pull this off, it's much more plausible after looking into it.
So let's say 1000 people follow this and at the beginning of the day they push the "correct" color. Now, by 2 PM you see Blue has a pretty decent lead. If your color is blue, you will probably try and cash in your points. If you are one of the other colors, you may hold off to see if your team will catch up so you don't waste your points on a day your team won't win.
That just lets the snowball grow.
FWIW, here's Reddit's schedule:
Purple - 6/19
Red - 6/20
Green - 6/21
Pink - 6/22
Blue - 6/23
Purple - 6/24
Red - 6/25
Green - 6/26
Pink - 6/27
Blue - 6/28
I'm pretty sure the first have been correct so far.