If you received any author rewards the last days, you may have noticed that a small amount of your payout was credited in STEEM. This happened because the SBD payout rate fell below 100%. Since SBD is backed by STEEM, the market cap of SBD must be way lower than the market cap of STEEM. The SBD payout rate is an internal mechanism in the STEEM blockchain to ensure this. Whenever the market cap of SBD is higher than 2% of the market cap of STEEM, printing of SBD is gradually reduced until it completely stops if the market cap of SBD reaches 5% of the market cap of STEEM. It should be noted that the market cap of SBD used for this threshold is calculated with 1 SBD = 1 USD and not the actual market value of SBD (which currently is a lot higher than 1 USD).
With the steep fall of STEEM below 2$, the relative market cap of SBD grew larger and the mechanism described above kicked in, such that up to 5% of SBD payouts where credited in STEEM. This wouldn't affect authors, if the value of 1 SBD would equal 1$. However as this peg is broken and the value SBD is a lot higher, payouts in STEEM reduce the total reward when calculated in Dollar.
Thus, we should be happy, that STEEM regained some of its value and SBD payouts are now back to 100% again.