Rewards down by 25% but hashrate unchanged

Hey all, I've been farming ravencoin on 2miners pool for a couple of months. I tuned t-rex miner in hiveos and was squeezing out about 52 RVN per day. However, for the last week or so it's been only ~38 RVN per day. The hashrate reported in hiveos remains the 27.5 MH as it always has been, and I have maybe 1 in 1000 rejection rate. Am I missing some fundamental part of how this is supposed to work or has something happened with ravencoin, 2miners, t-rex, or hiveos – or even the mining rig – that is causing the lower rewards?