What do you mean by deduction rate? Do you mean your traffic is getting scrubbed, or the % commission they take?
For example, if you show you are generating 1000 leads, does your aff network only show 900?
Or do you mean if you know the merchant is paying network $10 per lead, and your personal payout is $9?
It's normal for aff networks to take a small cut, but it's not normal to intentionally scrub. Ask your AM what's going on, and try to split-test the same offer across multiple networks.