Concurrency With Overloaded Methods

Consider the OverloadArray class provided below. Which statement best describes a potential concurrency issue arising from the overloaded updateScores methods?

public class OverloadArray {
    private int[] scores = {10, 20, 30};
    
    public synchronized void updateScores() {
        scores[0] += 5;
        scores[1] += 5;
    }
    
    public void updateScores(int index) {
        scores[index] += 10;
    }
    
    public static void main(String[] args) {
        OverloadArray oa = new OverloadArray();
        Thread t1 = new Thread(() -> oa.updateScores());
        Thread t2 = new Thread(() -> oa.updateScores(2));
        t1.start();
        t2.start();
    }
}