Thanks @JotikaT2 for this excellent clear answer.
The boxes for years 2021, 2022, 2023 were already populated (correctly), so there was nothing for me to enter. I was expecting same boxes for 2024 but apparently TurboTax automatically determines those values and whether anything from prior years could be used.
Upon checking the Forms view (Sch B Form 1116, 1116 Comp Wks), I see that indeed this is the case: FTC for tax year 2024 is again maxed out, so nothing from prior years could be applied.
