Sports are inherently unfair, always were. Nobody has any control over their genetics, having a longer stride or bigger lungs or a faster metabolism are advantages that can be difficult to overcome and vary widely even among people with the same assigned birth gender/sex. Especially in regard to kids & teens sports, most people can remember at least one kid in school who hit their growth spurt early and dominated at a variety of physical activities as a result. The simplest answer is to separate by height & weight instead of gender, it might not be perfect but it would be a hell of a lot closer than what we've been doing.