Difficulty increasing

hey miners

just a quick question maybe i'm going a bit crazy (probably)

But i have been mining for around 2 months now racking up a fare amount of RVN at a steady rate. But since some of the ETH miners migrated to mining RVN I've noticed my rewards/payout has dropped by about 50% meanwhile my mH/s hasn't. I know difficulty has gone up as a result of ETH miners but this doesn't seem to be adding up.

Has anyone else noticed this or is it maybe my Rig acting up