Inherited IRA and RMD

I was one of 3 children that inherited my mom’s IRA when she passed away in June 2020. Per the IRS rules I did not have to take an RMD in 2020, 2021, 2022 or 2023.  I took a distribution in 2024 of about 20% of the account balance.   When doing my taxes I entered the amount I took out and it then asks me the amount of the RMD.  If I enter the full withdrawal amount my taxes go up 25% of the withdrawal amount even though I already had 20% deducted from my distribution.   I already double checked that this is an inherited IRA due to death and the year of her death.   Should I enter an amount in the RMD field and if so why am I being double taxed in the amount ?