And conveyors will accept non-fluid items like dusts and other random crap. On top of this, a conveyor can't pull items from the input slot so it just stays there.

I'm not sure anything can be done since this is the same behavior as fluid-hatches directly in GT5u

Inherit behaviour from GT fluid tank logic.
It doesn't actually cause any issues though.

It does cause issues, since they just accept random crap from pipes causing them to need a item filter, which also requires power

Take the issue to gregtech then?