I have seen evidence of the roundness from the old "ships passing beyond the horizon" and the design of the heights of radar antennas and crow's nests to "see" the farthest distance.....All because of the curvature of the earth because the earth is the globe that it is.
And the only evidence that I have seen for a flat earth is from someone in Kansas looking out hiis window and thinking that the earth was flat was because that was all that he could see from his window........But I have known some people in the Navy from Kansas who have had the good fortune to have had some Sea Duty and know otherwise.