i can see the Contacts app nickname other people have assigned to their contacts in email replies.
ok, let me explain. my sister just replied to an email chain amongst our family. looking at her email reply in the Mail inbox window, i see other family member's names in the CC section. but if i click Reply All, and a new message box opens up, suddenly those same family members names change. instead of my mother's name, it says "mama," which i know is how my sister has our mother in her Contact app. instead of our aunt's name, it say "aunt so-and-so."
this is bizarre, and seems like a slight security issue. if someone is emailing someone else and they mean to hide the real identity of that person, but they use the persons real identity in their Contacts app, this bug would expose them. obviously, that's far fetched. but this just seems like a bizarre, sloppy bug that i would see someone else's private Contact names.
MacBook Pro M3
macOS Tahoe 26.6.2 (25G83)
Mail Version 16.0 (3864.700.51.1.1)