It is in this post under "rewards" and the first I know oft his being mentioned in the run up to the fork:

https://steemit.com/hf21/@steemitblog/hardfork-21-survival-guide

In fact, people with open payouts under $20 saw the post payouts drop 20-35% the day after the fork. Those above $20 increased - the bigger the payout, the bigger the increase.

Thank you very much for the upvote. I am not giving up :)