I cannot confirm this on android. google authenticator displays username@domainname below each OTP

Just to clarify, I am talking about the Site Name (above the code) not the email address below. The Email address used for the user account may not necessarily tied to the website domain.

If you look at other codes in Google Authenticator they generally present as:

**Site Name

1 2 3 4 5 6
Account Name**

However in Joomla Sites, it presents as:

1 2 3 4 5 6
Account Name**

in the examples above none of them are my email address or the email address of the user
they are all
USERNAME@DOMAIN

ah - sorry I understand now what you are requesting. Its the issuer param that is displayed above the number

https://github.com/google/google-authenticator/wiki/Key-Uri-Format#issuer

Unfortunately I tried to make the required change but even when using the samples directly on the doc site the authenticator app did not recognise the "issuer" - this was before I tried to add it to Joomla

I have the same issue. I had to disable two-factor authentication when switching to a Google Android-phone from my previous Sailfish OS-phone, and have not been able to activate it again. In the mean time I have updated the site to Joomla 3.9.8 and the problem persists.

You absolutely do not have the same problem. The "problem" referred to here is purely a cosmetic issue.

Your problem is because there is no way provided by google for you to "move" from one phone to another and it is expected that you have to create a new authentication when you change device. This is beyond joomla's control

Ahh.. Sorry, I thought the authenticator wasn't working. Obviously didn't read the description thoroughly enough. Then I agree it's absolutely not the same issue as in my case I am not able to enable 2 factor authentication with Google again. I don't know if it is beyond Joomla's control or not, but I don't have the same problem with Github. Anyway, leaving this thread now :-)

Please test PR #27368