Why do I have to pay to file this year with student interest and last year I didn't?

You must not have used TurboTax Free Edition last year. Free Edition did not handle the student loan interest deduction for 2018, and does not handle it for 2019. Maybe last year you used IRS Free File Program delivered by TurboTax. (Last year it was called Freedom Edition or Free File Program. Those names sound similar to Free Edition, but it's a different product.) IRS Free File Program delivered by TurboTax has a different set of limitations from TurboTax Free Edition, but it does handle student loan interest. It's at the following link, and the qualifications are listed there.

IRS Free File Program delivered by TurboTax