How do I update my Apple Account passkey to reflect a changed Apple ID?

With an issue that I'm aware has been going on for over 2 years among Apple users and almost a year for me, I'm now putting my foot down and hard.

You see, Apple allows its users to sign in to their Apple accounts with a passkey and also the ability to create a passkey to use for that Apple account in future. This is supposed to make things more secure, and more convenient too rather than typing in a long password as it often involves the use of biometrics, if not always. Other websites, like Amazon, also allow users to set up and use passkeys. Now, once you set up a passkey on any website on any of your Apple devices, it will be stored in your iCloud Keychain (now called Passwords), and iCloud Keychain is stored, you guessed it, in your iCloud. You can manage all of your saved passkeys through the Passwords app. It all sounds all good so far, until you realise the problems..

You see, passkeys get saved. The usernames or email addresses attached to passkeys aren't live-updated with the platform or anything. As an example, if I set up a passkey for TikTok and it was saved in my iCloud Keychain, if I were then to update my username or email address in TikTok at a later date, it wouldn't reflect on my passkey and the only way of updating it there would be to delete the passkey and set it up again in the TikTok app. This is quite easy to do as deleting a passkey can easily be done through the Passwords app. And in addition, even if you weren't to bother with any of that, your passkey would still work just fine, except for the fact that it may show your previous TikTok email address or username, but it'll still log you in fine, and once it bothers you enough then you may delete the passkey and set it up again as described above.

But the problem arises when we start to talk about our passkey we've got saved in our iCloud Keychain that's for our Apple Account. You see, Apple have made a clear attempt of trying to be sleek and slick with it, and what they've done is they've actually not allowed their users to see their own passkey for their own Apple Account in the Passwords app, and maybe even the Keychain Access app from what I've been able to gather. This does have its pros, like how you can ensure an Apple user won't accidentally delete their Apple passkey, but the negative has been brought up enough times now, and I've had enough of this issue having no responses to by the Apple community, no knowledge about by Apple Support, and, worst of all, no known solutions from both within and outside Apple.

Now, something you may also be aware of is the ability for one to be able to change their Apple ID. This is entirely possible and many have done it successfully in the past, no issues there. However, once mixed with the fact that you can also set up a passkey with your Apple Account, it gets messy. So, let's put this into a step-by-step scenario to demonstrate where the issue lies.

1. I create an Apple Account, and the Apple ID is coolappleid@icloud.com.
2. I sign in to my Apple Account on Apple's website, and I get to create a passkey.
3. This passkey gets saved under the email of coolappleid@icloud.com.
4. I can't see where this passkey is, but I just know it's there as I'm able to sign in with it whenever I sign into Apple's website.
5. One day, I have the desire to change my Apple ID from coolappleid@icloud.com to coolerappleid@icloud.com, and so I do so.
6. The email coolappleid@icloud.com now no longer functions and my new Apple ID is now coolerappleid@icloud.com.
7. I one day sign into the Apple website using my passkey.
8. Oops! It seems that when attempting to sign in using my passkey, it is still showing my previous Apple ID, coolappleid@icloud.com! This is because my passkey was created before I changed my Apple ID to coolerappleid@icloud.com.
9. I struggle for a solution, as my passkey doesn't appear in the Passwords app as it's been hidden on purpose by Apple.
10. As my passkey is however synced through my iCloud Keychain, I go and try to sign in to the Apple website again on one of my other Apple devices, and I see the same problem again where the Apple ID that is shown is the old one, coolappleid@icloud.com, when it should show coolerappleid@icloud.com.

[Re-Titled by Moderator]

Original Title: Horrific situation concerning the display of one's old Apple ID when signing into Apple Account using passkey