Looks like it is still not fixed. I'm not sure the law itself is bugged, because I've had "opponentrecyclingsciencepercp" effect from 3 different sources (said law, Debris analyzer modules and Take trophies tactic). I've arrived on the node that had one hostile Behemoth and three 18CP fleets, that consequently attacked mine in same turn. I've received exactly 3x as much of both dust and science that I should from the first battle, and twice as much on second and third time.

Maybe there is a bug on how "per fleet" part is applied? Because number of enemy fleets on the node is the only part that diminished between battles. But I'm not too sure on this one, as multiplier part is hidden.

To illustrate my calculations, this is the reward I've got from the first battle

I've had republican Spiles of war enabled

Two coordinators each hosting one Debris analyzer module (tooltip already has slot multiplier effect applied)

and applied Take trophies tactic each time

I should've receive

(100 + 30) * 18 = 2340 Dust

(100 + 40 + 40 + 10) * 18 = 3420 Science

Instead I received exactly three times as much

7020 / 2340 = 3

10260 / 3420 = 3

Same goes for second and third battle, although I've destroyed less CP and my coordinator was destroyed in second battle (-1 Debris analyzer), yet still reward was exactly two times bigger then expected calculation.

per destroyed cp is based off of cp youve lost I think. also, Ive noticed for some reason the rewards for these types of things are multiplied per ship in your fleet

No it's not. It's per opponents CP, just as description states, I've verified that multiple times with different destroyed CP numbers.

LMAO, I've figured out my case. It multiplies each time you (re)watch the battle.

Let's say I have +190/CP effect and I'm destroying 10 CP. If you simply autoresolve battle without watching it, tooltip will show correct number of +1900.

If I watch the battle, I will recieve double amout of +3800. If I rewatch it again (!) it will be +5700.

And this is purely visual bug, it doesn't increase actual empire dust / science pool. I think game just doesn't clear variables and increment happens each time battle result screen is called to show up. Once for autoresolve and each time you finish watching that battle.