The law says that calculating the Premium Tax Credit for one tax year uses the previous year's Federal Poverty Level. So as you found out, the 2019 tax return uses the Federal Poverty Level for 2018 ($16,460 for a family of two). So the program is accurate, and you were misinformed as to what numbers to use. The 2019 Federal Poverty Level ($16,910 for a family of two) is used for 2020 tax returns (filed early in 2021).
