It can't easily be described by a constant so it has to be a term `batchSize^0.1`. Probably this should be in the describtion instead of the tooltip.
In the Han CC i changed `0.8 * 0.75` to `0.8 - 0.2` so it could also be described the same way. In vanila 0ad the final value didn't change (it's still 0.6) but in a mod which multiplyes the modifier by another factor it might change.