Is it possible our Letter 6475 has an error?

We are filing married filing jointly for the first time this year and we received two separate letter 6475. Mine stated that I received $2800 on the third stimulus (which is correct) and his  stated that he also received $2800. However, his deposit was only for $1400. Now, I did have a second child who is now claimed as the second dependent on our 2021 tax return but I was still pregnant with him when we received our third stimulus so obviously he was not on our 2020 tax return as a dependent. Our 2021 tax return is now delayed but I can’t figure out if this is our fault or if the IRS made an error?