I can confirm I am getting consistently an average reward only half what I would expect for my hash rate.
I get 1/4 the average reward post halving where I would expect 1/2 the pre halving reward.
It is statistically improbable that 'bad luck' (random chance) could produce this for so many 24hr periods.

Bad shares is down to ~1%, so that doesn't appear to be a problem.
My only clue from the interface, is that Est. Shares is listed as 400%, 800% or more, much of the time.

When I was getting 4x the reward, pre halving, with other variables fixed,
the interface did not show that as often.

A problem somewhere with the  math & computing?
(math is hard, there doesn't have to be any 'scam' going on).

Anyway, I'm switching to my backup pool,
until I read here that something has been changed.
Then I'm happy to come back and test again.

Thanks guys.