Stroke Aligned to Outside of Filled Shape and Fill of Shape Not Aligned
When aligning a stroke to the outside of a fill area, there are areas in which the fill area is incompletely filled, or the fill extends beyond the stroke.
Mac OS 12.0.1 (21A559)
Illustrator 26.2.1

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There is another example of the same behavior, in the file shared by Doug Roberts.
There is a certain limit of the size — if the object gets enlarged a bit, it works fine again. Changing the alignment of the stroke to normal Centered makes the fill behave again. Changing the opacity does the same.(Edited by admin) -
I confirm that, it really has a problem like this.
While it gets fixed, there is workaround solutions to this. — work with a larger scale. The bug seems to not affect shapes if you scale the object up. Scale it down later, after you expand the artwork before you producing.
Generally it seems to be a precision problem.
If you achieve the same effect by using a second black fill below the green one with an Offset Path effect to this black fill — it gives the same problem, even worse :(