Byzantine eco Bonus incorrect - its the same as italians

The Byzantine Eco bonus of -33% cost for imp research is incorrect. what’s actually happening is that they have the same bonus as italians - 15% less for each age research.

Cant confirm that. When I start with high ressources 1000 food and 700 gold I lose 667 food and 534g which is exactly what 33% of 1000f and 800g is