Not sure to be honest, however wanted to test in a clean default template project.
a simple cube as physics enabled, projectile collision as default with an add force.
a physics field as default with metadata filter for destruction only effect (same one)
physics flight is normal on this one. If a cluster hits the projectile it is effected as you described as a new problem cause you started with field system as problem space.
however that can be also neglected as below.
make a new channel for particles , choose what channels should effect in your game.
I left ofcourse projectile channel uneffected cause it is what we want as problem space.
On your geometry collection search for collision profile per level (per destruction level what collision should behave)
Notice now also particles not effecting the flight of projectile.
However you are right that there is no much detailed information around the topic unless you deep dive into search in code or net. As mentioned its around collision and response channels and please for next time it can be more easier to help you out (if its something that anybody has info about) use descriptive problem writing and images if possible, it would be much more effective process if we understand what exactly is wrong after all understanding the problem is half solving it.