From the latest IRS update:

Including current year returns, as of April 16, 2021, we had 16.1 million unprocessed individual returns in the pipeline. Unprocessed returns include those requiring correction to the Recovery Rebate Credit amount or validation of 2019 income used to figure the Earned Income Tax Credit (EITC) and Additional Child Tax Credit (ACTC).

--Of course they're lying about returns requiring "correction" to RRC; a return with credit based on an added 2020 child is correct, but they don't believe you anyway.