I had a post in the forums explaining this problem and its solution but someone more concerned with which version of the software was used than whether the post addressed a problem removed it. So I'm posting it here again so the next time someone has this problem they can find it (hopefully).
If Apple took its UX development as seriously as they do their curation of forums posts this would be a non-issue.
Original post: No matter what I do, the Mail app continues to send the wrong name when I reply to an email. This is incredibly frustrating and I'm hoping someone can suggest something I haven't already tried.
What I've tried so far:
Contacts
I've edited my contact card to not have the wrong name anywhere. Notably, searching for the wrong name still brings up my contact card. Even though it doesn't show in any fields.
Mail settings
I've gone into Settings->Mail->Accounts and ensured the Name field has only the correct name.
iCloud settings
I've gone to icloud.com, opened the Mail app, and clicked the gear icon to bring up settings. The right name is listed there.
I'm pulling my hair out trying to find where this name is hidden. I would rather it not add any name to my email From line if it can't use the correct one.
Solution: in Settings->Mail app->Accounts, make sure you actually enter your name in the fields. If your contact name is there but it's grey, indicating it was the default, this may not be used.
Note: I'm putting this under Accessibility and Inclusion because making it difficult or hidden to change your name on email could end up deadnaming someone. Which is not cool. It's bad enough y'all make given name and surname required fields when not everyone in the world uses a surname.