Has anyone else experienced a dramatic change in estimated refund AFTER submitting payment? My refund after submitting payment reduced 6k!!!

My estimated refund for fed and state combined was 6k more than after I paid to process my taxes. I didnt change anything, there was no corrections after the review. It said my estimated was the same after the review. I feel this inflated refund is a gimmick then they provide the real amount after payment. What the benefit is for this i dont know. Im going to have to file taxes regardless.