Technically, yes, "you broke the underpayment law."
If you have interest income that is extremely unpredictable, you can do a couple of things to not have to actually pay a penalty next year. As you mentioned, the one way to avoid the underpayment penalty is to pay 100% of your tax liability....this means in the prior year. This does go up to 110% if you make more than $150,000 a year. What this means is, if you look at like 16 of your 1040 for 2024 and it says $12,000, then you would need to pay $12,000 (Or $13,200 if you make over $150,000) in 2025 to not have a penalty. You would answer the penalty questions again like you did this year but you would not pay the penalty. Pay as you go means every quarter, not just once a year. If you do it perfectly, then you would not owe anything at the end of the year when you file your taxes.
You can increase the taxes you have withheld by updating your W4. If you owed taxes this year and you do not want to pay a penalty, then it would be a good idea to divide the amount that was due to the interest by the number of pay periods you have and have that amount withheld as an extra withholding.
You can also choose to make estimated payments when you get the interest payments instead of having more withheld at work. Depending on how much interest you are earning, you could send in 30% of what you get as an estimated payment if this is how much extra you paid. This may allow you to hit that 90% mark as well or even the 100% of 2024.
Depending on why you are not having to pay the penalty, you may or may not have form 2210 in your return. This would be the form that requests the waiver from penalty.
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