Yearly rent increases on a preferential rent?

I have been living in a rent stabilized apartment since 2020. First year I paid $1852 and at lease renewal time in 2021, I asked for a discount (preferential rent) due to economic hardship. The LL approved it and I paid $1500 for 2021. However, when it came time to renew in 2022, they wanted me to pay $1600 which i did. In 2023, they asked me to pay $1700 and in 2024, $1775. For 2025, they want to negotiate a price between $1,850-$1,900.

I did some research last night, based upon another person's post in this subreddit, and I'm wondering if I've been overcharged from 2022-2024? Are they only legally allowed to increase the preferential rent each year according to the percentage from the rent stabilization board? Because if so, they haven't been following that and by my calculations I have been overcharged and I have overpaid $4,471 over those 3 years.

I requested a copy of my apartment's rental history yesterday. I also submitted an online request with the NYC Bar Legal Referral Service yesterday, but received an email denial from them saying that they don't have anyone to represent or advise me.

I'm just trying to find out for certain if I would have a valid complaint, not sure what my next steps are. Thank you in advance!