IRA contribution being limited

I am retired; I earend $1725 on a consulting job during 2023. I planned to put all of it into my traditional IRA.

 

TurboTax says I can only deduct $1603, and that if I contribute 1725, the difference will be a non-deductible excess contribution. 

 

Since the contribution seems to be limited, I will only contribute $1603; I'm only doing it for the tax advantage, and I don't need the money to be available soon. But I would like to know why they are limiting the amount of the contribution. I was limiting it to the amount of earned income I have, I don't know why I cannot contribute the entire amount to the IRA, as I did last year with a larger amount.