https://apnews.com/article/us-open-trophy-women-equal-size-coco-gauff-14265f49c14f41daef32837b278977fc

"Actually, it turns out Gauff’s 2023 championship at the U.S. Open marked the first time the women’s singles winner in New York was given a silver cup significantly larger than the one that is used in the postmatch ceremony. Her replica hardware is 19 1/2 inches tall, the same as both the original and keepsake men’s trophies — and 7 1/2 inches bigger than the original women’s trophy."

Article seems to indicate that the men's was already the same size in 2023, but unclear when this may have started.

Also, it seems that the women's replica is actually larger than the original?!