How this solution beats 100% of the submissions?

Can anyone explain the time complexity of this solution and how this beats 100% of the solution? Isn't the time complexity should be n^2? So how this so fast?

class Solution {
    public int[] twoSum(int[] nums, int target) {
        
        for(int i = 1; i < nums.length; i++){
            for(int j = i; j < nums.length; j++){
                int sum = nums[j] + nums[j - i];
                if(sum == target){
                    return new int[]{j , j - i};
                }
            }
        }
        
        return null;
        
    }
}
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