There must be a way in whatever IRS free file option you're using to see the return itself. I don't know what it is, but all programs I am aware of provide that.
But I'm pretty sure I know what is going on anyway.
When you did your taxes before, you received $2,115 too much in APTC. However, because your income was between 200% and 300% of the FPL for your family size and location, you only were required to repay $1,600 of that due to the repayment limitation (see the instructions for Form 8962 line 28 and the associated table 5 on page 16 of
https://www.irs.gov/pub/irs-pdf/i8962.pdf).
Then the law changed due to ARPA, and you didn't even have to repay the $1,600. That's the difference you're seeing.
Does the program you're using tell you your AGI? If so, you can probably take that number and see if it is between 2x and 3x the FPL for your family size and location for 2020. See this link:
https://thefinancebuff.com/federal-p...obamacare.html
For example, if you lived in the continental United States (which it appears you do) and had a family size of 2, then you'd use the $16,910 number, and your AGI was probably between 2 * $16,910 and 3 * $16,910, whatever that math turns out to be.