we can't see your return nor input so can't say what happened. you may need to see a pro so the past errors, if you are correct, can be corrected. this may require filing form 3115 which many uninformed taxpayers can not handle.
Wild guess here based on no facts.
I am assuming this is for residential rental real estate, and that the property itself is the only asset listed in the Assets/Depreciation section of the program.
It "sounds" to me like you (or someone else) changed the "cost of land" amount to a higher amount in that second year.
IRS Publication 946 at https://www.irs.gov/pub/irs-pdf/p946.pdf covers how to depreciate property. For residential rental property use the worksheet on page 38, and table A-6 on page 72 applies to residential rental real estate.
If things are wrong, then because this occured so long ago you will need to seek profesional help to fix it. You can not use TurboTax for this, as TTX only supports their software for the current tax filing year (now 2020) and three years back. Additionally, because of the time that has passed, amending isn't an option. You'll have to file IRS Form 3115 - Change of Accounting Method, to fix this. While TTX 2020 does include this forum, it is not simple by any stretch of the imagination. So if you don't know what you're doing, seek professional help.