Is re: tax year 2023: Used an IRA MRD to satisfy 403b MRD. Wrong. Do I need to take an MRD from the 403b (for the amount I should have taken) prior submitting IRS form?

Yes, if you didn't take the RMD from the 403b then take it as soon as possible. The distribution will be reported next year on your 2025 return. 

TurboTax will give you the option to apply for a waiver in the follow-up questions:

1. Login to your TurboTax Account 
2. Click on "Search" on the top right and type “1099-R”
3. Click on “Jump to 1099-R” and enter your 1099-R for the IRA
4. Continue through the questions.
5. On the "Review your 1099-R info" screen click "Continue" after you added all Form 1099-Rs
6. On the "Did You Miss a Required Distribution From Any Retirement Accounts?" screen select "A 403(b)..."
7. On the "Total RMD for all other 403(b..." screen enter the RMD from your other IRAs (where you didn't take a distribution from).
8. Say "Yes" on the "Was a corrective distribution made for your 403(b) accounts"
9. TurboTax will walk you through the steps to apply for a waiver.

Please see Can an account owner just take a RMD from one account for additional information.