Advanced Child Tax Credit and divorce

I automatically received a full $3000 of the advance child tax credit into an older joint bank account.  I did not give my ex any of this money, since per our divorce decree I get to claim both children for the 2021 tax year.  The IRS's form 8812 that was mailed only has half this amount on it.  In researching this, I found that the IRS is automatically splitting this amount for each spouse.  What amount do I file with, the correct 3,000 that I did receive or the incorrect amount that the IRS put on the 8812 letter?