new Herb & Sprout effect is bugged??

[summertime]

darknacht at roughly 228 H&S had following result:
"2 50%
3 25%
4 15%
5 10%"

My character at 113 H&S had following result:
67 pots: 19 x 3, 48 x 2 => 28.35% chance to get 3


this means:
Expected value for darknacht = 0.5*2 + 0.25*3 + 0.15*4 + 0.1*5 = 2.85
Expected value for my = (48/67)*2 + (19/67)*3 = 2.28

this is to be compared to the "base case" of expected value of 2.

so at roughly double the the H&S, the additional expected value increases from (2.28-2 = 0.28) to (2.85-2 = 0.85) that's a tripple increase! This is concerning because the devs should make it so that it yields diminishing returns, which isnt the case here. so there may be a bug somewhere or just either i got very unlucky, or darknacht got very lucky

even if we compare the numbers (2.28/2 = 1.14) vs (2.85/2 = 1.43) we notice that 228 H&S increases base case by 43% while 113 H&S only increase by 14%, which is strange. One would expect perhaps the ratio between those % to be something that is tempered such as sqrt(228/113) = 1.42 times larger which would mean that the 228 H&S should only have given 1.42*14 = 19.88% increase.
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as for bugs: maybe there are skills and profficiences that shouldnt affect yield but due to bug affect yield
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edit seems like no bug according to dev

[DarkNacht]

With the potting yields we are still calculating off a fairly small sample size so there will be a lot of variation based on luck, we will get a better idea of the numbers once once more data has been collected.