did you elect not to file form 1116 for the years 2016,2017,2018 and 2019? if you did you voluntarily gave up all carryover for the years the form was not included.
from IRS 1116 instructions
If you make this election, the following rules apply.
You can't carry over to or from any other year any foreign taxes paid or accrued in a tax year to which the
election applies
if you did not make the election, then the foreign taxes used for any year are those that arose in that year. the excess becomes a carryover. example 2016 arose 900 used 600 carryover 300. 2017 arose in 700 used 600 carryover 100. FTC's may be carried forward for 10 years. so any remaining 2016 carryover would disappear for 2027.
