When did you attempt to e-file an amended 2021 return? If you did that today--or recently--it is not possible to e-file a past year amended return. An amended 2021 return must be filed by mail.
Mail is using a mailing service such as certified mail so you will know it was received. It will be a long time before the IRS processes it.
Do not expect quick results from amending. It can take four months or more for the IRS to process an amended return.
You can watch for information here:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1