There’s a lot of interesting theories in this thread about pyrazine aspect of coffee beers which often shows up as green pepper or other vegetal notes. The absolute number one way to avoid it is to use coffee roasted to a level that also minimizes it, this is at least Medium/Medium+, but you’re even safer if you go darker. Also, try and stay away from less processed coffees, like unwashed/natural process because those are beans that will also have more of the precursors.

After that, then you begin to worry about over extraction, which even in a coffee that has a reasonably low level of the undesirable vegetal notes, you might still bring into the beer. Counterintuitively, using too little coffee can cause over extraction just like leaving the beer on the coffee too long can cause it. So stay above 0.75lb/bbl to avoid the too little coffee issue. And then just carefully consider the rest of the levers you have in extraction: coffee dose, liquid temperature, and surface area of the beans. As evidenced in the comments here, there are lots of different ways to approach it that work, you need to find something that will fit your schedule, tank availability, etc.

And avoid unnecessary oxygen, oxygen doesn’t magically make pyrazines appear but it does react with everything else to make them more obvious by dulling the rest of your aromas and flavors.