Well, I was sure that prior to 2.0, the percentage reduction was both in the module description and the entity tooltip affected by such module ... but I was wrong.

Hello.

The efficiency module do not show in its description nor effect list that it reduce the pollution.
On 2.0.73.84377 (latest steam experimental on windows) base game (no mod, no space-age) using the prototype inspector, the effect list properly show its -30 consumption but the pollution effect ...