Minecraft: 1.19.2
Fabric: 0.14.9
FabricaeExNihilo: 0.1.8+mc1.19.2
REI: 9.1.550

I haven't checked whether the problem is that REI just displays incorrect probabilities or if the probabilities themselves are incorrect.
Sieve probabilities for iron, diamond, and netherite meshes seem to all follow diamond rather than their own.
Using iron from gravel as an example, the iron_from_gravel recipe seems to indicate that iron mesh should have 0.25, 0.15, 0.1 probabilities, and netherite mesh should have 0.75, 0.66, 0.5. But REI shows them both with 40%, 40%, 40%, same as diamond mesh.

I did some refactoring around sieve recipes in the latest update. Might have broken it