Uber Arbiter drop rates

So i killed 500+, maybe even 600+ uber arbiters and the drop rates of the prism of belief just don't make sense to me.
From some sources i heard it's around 26% then other people did some testing and it was 8-9% (which i don't believe it is considering the price of the unidentified jewel compared to entrance price). I would assume it's closer to 20% than to 10% considering it's "uber" + drop rate in previous seasons was 21%~ on highest difficulty.
The weird thing i noticed is that i rarely had steady drop rate of these jewels (so let's say i do 20 runs - i loot 3-5, then another 20 runs, another 3-5).
It was absurdly often i had dry streaks of like 10-15 to then get 3-4 in 6-7. Or i got 13 in 40 runs and then i got 2 in 40. I know it can happen and it should happen but the frequency was just too high.
During these 500+ runs i had at least 5 dry streaks of 20+ arbiters of no prism drop. Even counting the drop rate to be 20% it's 1,15% chance to get dry streak of 20. So this happening 5+ times in 500+ runs just doesn't make sense at all.

Can we get the info of the real drop rate?
And if the drop rate is fixed? Or is it being changed from day to day because my experience (tinfoil hat on) just makes me believe that.

Lets say you flip a coin 99 times and get heads 99 times in a row

Do you believe that on 100th flip you're guaranteed to get tails? That's how your post reads.

p.s. you are not guaranteed tails on 100th flip : )

[Removed by Support]

The post is about how the eventual average drop rate was driven by "anomalies" in drop rate. It is extremely unlikely to go multiple 20+ streaks of not hitting and then going back close to average with another set of extremely unlikely streaks of hits.
The average at the end was something between 16-19% drop rate so i'm not bragging about not profitting.

It's just the experience of the farm which felt off.
If the drop rate is fixed than i'd like to know what it is.
If the drop rate changes day by day then i'd also like to know, even though it sucks because how on earth would this boss be attractive to farm if you go into unlucky streak and loot 3 jewels out of 40 arbiter runs (like i did). It shouldn't be the farm that you have to get 500 divines to even start thinking about profitting eventually.

Drop rates rarely ever change. Usually some tweaks come with launch of new league or a hotfix on an obvious outlier. But no hidden "when the sun reaches high noon make unique jewels more/less common" type stuff.

To get a proper sampling of drop rates, I'd want 300 - 3000(daily if trying to test day to day change) points of data to quiet the rng noise and see the trend.

20 runs isn't really enough to confidently estimate a days drop rate (assuming it does vary)

in short, RNG gonna RNG.