Having 2 Nakalim cuts it down to 10% unless you are playing 8 or more players.
Otherwise, having just 1 Nakalim in a game cuts your Omniscience trait in half across all Tier 1 and Tier 2 techs. Tier 2: Botanical Scanning, Eukaryotic Sap A few tier 1 and tier 2 technologies are not blanketly affected by the Nakalim because the Sophons have a variant that ignores the default technology:
