Space exploration recently did update some recipes, to make sure productivity modules do not affect byproducts anymore. However, helmod still does it, while factory planner properly decreased values.
https://cdn.discordapp.com/attachments/419527276875481111/1084669880629985481/image.png pic for comparison. Upper line use prod modules to produce main product, lower line is without modules at all. Due to this, recipe chain that helmod had no problems with before latest se update now shows very incorrect numbers :(

Hello, when you add productivity the ratio between of all ingredients is preserved, the ratio between of all products is preserved but that reduce required quantity of ingredients to produce more products.

Normal recipe
20 Vitamelanges = 2 woods + 4 stones + 20 Vitamelange nuggets

Productivity 80%
20 Vitamelanges = (2 woods + 4 stones + 20 Vitamelange nuggets) * (1 + 0.8)

is the explanation sufficient?

Helfima: Some products can be excluded from productivity by setting catalyst amount. I'll check this is working correctly.

https://wiki.factorio.com/Types/ItemProductPrototype

catalyst_amount
Type: Types/uint16

Default: 0

Amount that should not be affected by productivity modules (not yielded from bonus production) and should not be included in the item production statistics.

Fix for this will be included in the next version of Helmod.

Ah yes I forgot this catalyst

Fixed in Helmod 0.12.15