2 Factor Authentication Old Apple ID.

When I try to sign into new devices, or for instance this forum, I am prompted with a 2 Factor Authentication request asking me allow a device to sign in. What I see in the message that pops up onscreen is my old Apple ID email address (Not my current email address I use for my Apple ID).

My current Apple ID email address ends with @protonmail.com and my old Apple ID ends in @hush.com (See Image). This old email address is no longer associated with my account, it is not listed in my registered email when I check at appleid.apple.com.

This is causing problems.

I am regularly being prompted to re-signin to my devices and when I use the current and correct password for the @protonmail.com Apple ID I receive a message onscreen that this is the incorrect password. So, I try the current password for the @protonmail.com Apple ID again and I also try the old password for the @hush.com Apple ID and I recieve a message onscreen indicating that my Apple ID Account in locked. Then I'm prompted to change my Apple ID password.

Changing my password enables my devices to work but later on I am again asked to sign into my device with the @hush.com address displayed onscreen.

I have no idea what to do.

I disabled 2 Factor Authentication and then re-enable it but this didn't help.

Any ideas?

Any help is very appreciated. :-)