The H-index is designed such that posts with few upvotes cannot decrease the H-index. Since it is defined as the largest n such that you have ≥n posts with scor

The H-index is designed such that posts with few upvotes cannot decrease the H-index. Since it is defined as the largest n such that you have ≥n posts with score ≥n, adding another low-scoring post doesn't decrease the H-index.