So I'll bet that cash back was always a lower rate. Their terms are rather evasively written, but my reading is that they have two different redemption categories, both called "statement credit":

1) "eligible Rewards Partner transaction" statement credit

2) general "Cash Back Statement Credit"

From the link you provided, they tell you that 2) can be a lower rate, but they don't tell you what that lower rate is. But I did see the recent reddit discussion saying that it's 0.7 points.