Yes it is still the same. Up to 85% of SS can be taxable depending on your other income.
If they say more of your SS is taxable it's because they increased some other income. A common thing they increase is the taxable income of any 1099R you had. Either you missed entering one or your reported the wrong taxable amount. Or it showed up on the wrong line so the IRS missed it.
Check 2018 1040 line 5a and 5b for Social Security and line 4a and 4b for retirement.
