I had to identify myself on March 23rd for my 2018 taxes. I did that and when should I expect that payment since I've already received my 2020 taxes?

Only the IRS can tell you what is happening with that 2018 refund.   TurboTax does not receive any information about your tax return after it has been filed.

 

To call the IRS:IRS:  800-829-1040  hours 7 AM - 7 PM local time Mon-Fri

Listen to each menu before making the selection.

First choose your language. Press 1 for English.

Then do NOT choose the first choice re: "Refund", or it will send you to an automated phone line.

Instead, press 2 for "personal income tax".

Then press 1 for "form, tax history, or payment".  

Then press 3 "for all other questions."

Then press 2 "for all other questions."  It should then transfer you to an agent.

 

You're lucky you got your 2020 refund. that's a good sign.

IRS is way backed up on special situations. Just wait. It could take months for the backlog to clear