I've been watching it closely, and it seems to be more a decrease in Steem amount. I don't know the reward mechanism in detail enough to be sure, but HF19 is certainly at the root of it. Probably it's because there is a lot more stake voting for posts now than there was 2 weeks ago, and it's been pulling a disproportionate amount of STEEM out of the reward pool.
Gentlebot and I still have some more things to discuss.
i think your more stake voting for posts now the argument is correct. its fun playing with the gentle one, i played a little with him today as well. :D Code my steemit account in it and ask him to upvote everytime i comment. hehe