You changed something that you should not have changed most likely. Now if 2019 taxes is your first time using TurboTax, then you did not enter the correct information from the 2018 tax return. Specifically the 2018 IRS Form 4562 that prints in landscape format and is titled "Depreciation and Amortization Report"
Another possibility is that you entered the wrong cost basis for an asset, and the cost basis you entered was lower than it should have been.
Another possibility is that you incorrectly claimed personal use days.
As you can see, there's all kinds of possible reasons for this. So you need to provide more details. Just asking "why" doesn't provide anyone with any facts to work with.
