Form 1116 excess foreign tax credit - how to find "Amount Used"?

I have an excess foreign tax credit for 2024. Desktop Turbotax H&B tells me I might need to file an amended 2023 return for a carryback, subject to some conditions. My question: where do I find this "Amount Used"? What line on what form? Should I be looking at the 2024 return or the 2023 return? TIA!

 

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