I agree that they are effective regardless of whether or not they are tracers.
But looking at the videos, every streak has an impact and there are no impacts without streaks. So every round fired by the Bradleys in Ukraine is a tracer. Maybe the U.S. Army didn't do it that way, but Ukraine does.
But it isn't clear what they are hitting. An effective round fired into a pile of dirt or into the ground of an open field still just moves the dirt around. There may be actual value in that as covering fire, but it is still a different thing than hitting vehicles or people (including close enough to injure) or fortifications. And from the videos it is hard to tell which is which.