Just to confirm, what numbers did you run, have your figured your "safe harbor" taking into account prior year tax also; see Form 2210 lines 1-9 which shows the calculation; you need to have paid the smaller of 100% of 2024 tax (110% if AGI > 150k or 75k if filing MFS), or 90% of your 2025 tax.
IRS by default assumes your income and tax due was even through the year per quarter so whatever amount of the safe harbor is underpaid and due via ES, divide that by 4 and that was the quarterly payment that is late for Q1-3 but still on time for Q4. Pay Q1-3 i.e. 75% of the total ES ASAP to stop that penalty accruing further, and the remaining 25% of it on time by 1/15/26 (submit electronic payment via irs.gov if able, avoid sending checks and vouchers). At this point you're roughly 8 months late on Q1, 6 months late on Q2, 3 months late on Q3 so the penalty will be roughly 7%*(0.25*(8+6+3)/12)=2.48% on the total ES due.
If your income was uneven thru the year e.g. Q4 Roth conversion or cap gains, then you can try and reduce the penalty when you file using Form 2210 Annualized Income (AI) Method where you have to calculate your AGI/withholding/Qual Divs/LTCG by quarter (uneven - 3/31, 5/31, 8/31, 12/31) which is extra work but if significant penalty may be beneficial. Turbotax will initially calculate penalty using the default method (check your 1040 line 38 for that outcome), then you can work thru other methods under Other Tax Situations / Underpayment Penalty to see if AI method is beneficial and adopt it (you could also plug in rough estimates for the AI method calculations to see if it helps, then go back and refine it if you chose to use that method).
