Replying because I found this when searching for the "balance due using computer figures" and "balance due using TP fig per computer" difference.
I received a CP71 saying I owed taxes for 2020. It took me a few hours researching and speaking with a very helpful person from the IRS. In my case I did not account for all of my 2020 EIP payments. I based my EIP amounts on what was shown on the IRS website. Silly me, that was just my EIP payment and not my spouse's. When I doubled the amount on the Recovery Rebate Worksheet I came to the same balance due using computer figures.
I hope this reply can help someone else save time trying to figure out what happened if they made the same mistake.
