Note that my skepticism is based on personal experience... as a graduate student ~25 years ago I noticed a similar pattern in some simulations that I was running for my thesis, and I had an absolute panic attack over them. My advisor said "run more simulations" and as more were added the weird sine pattern went away.
Yeah, that's what I was getting at with some of my other comment.
Even a 200 count exposing a wave like that is worrisome, because it does seem to be exposing *something* of the algorithm behind the generation... (and seeming even to swing reliably up and down through a 'full' cycle every 50 rolls or so...) but it is entirely possible that as you carry the sample into the thousands and beyond, that distinction will dissipate. I don't know.
So people know, the number gathering I conducted was done using the goblin courtyard and sanctum; I tried to gather the results in one contiguous string, actively avoiding advantage and disadvantage (since the combat log doesn't show both rolls), but sourcing the rolls in order, and thus including enemy rolls as well as my own characters'.
But as pointed out, there's a lot we don't know, and can't know - we don't know what causes reseeds on the RNG, or whether it's using independent generation seeds and methods for enemies and players, just for example.
The results are disturbing because of how clear they show up, compared to how indistinguishable the other sets from other games are, but we can't know what is causing what I'm seeing, or why.
I have indeed submitted this as a bug report to Larian's bug reporting form.
