Just looking for info - why do some boosts show as a percent, while others act as bonus production you don't see ? (policy cards vs Kilwa for example)

[Tunnah]

It's not important or owt, it just kinda bugs me. Monopolies got it stuck in my head - the money one shows as a percent np. But the production boosts don't.

And the modifiertypes themselves - they both lead to the same effect!

Gypsum production boost
MODIFIER_SINGLE_CITY_ADJUST_BUILDING_PRODUCTION
EFFECT_ADJUST_ALL_BUILDING_PRODUCTION_MODIFIER

kilwa
MODIFIER_SINGLE_CITY_ADJUST_BUILDING_PRODUCTION_MODIFIER
EFFECT_ADJUST_ALL_BUILDING_PRODUCTION_MODIFIER

I'm just curious as to why some show up in the numbers, and some are applied as a bonus.