Whether the IRS rejected it, or TurboTax, there was a reason, and probably included a code if a clear description was missing. I would need more info to help.
Consider using TurboTax's help tools.
Rejected: xx/xx/19
Filed Federal Tax Return
TurboTax
Federal Refund: $x,xxx
You have been answered in your other thread. You need to print, sign and mail your 2018 return since it was rejected. If you do not mail it in by April 15, 2022 you will forfeit the refund forever.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.
Federal and state returns must be in separate envelopes and they are mailed to different addresses. Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.