What do Channing the default domain do?

I wanted to know what changes occur when the default domain is changed ? Does it only change the login for Yunohost?
I ask this because as the admin interface of Yunohost works with all registered domains.
Eg. domian.tld/yunohost/admin will point to admin
subdomian.domain.tld/yunohost/admin will point to admin
domain222.tld/yunohost/admin will point to admin too

Can’t this be implemented with Yunohost login too? So that the need of default domain can be eliminated.
This is needed as the default domain can not be used for installing apps like wordpress and other blogging apps on the default domain because domain.tld/yunohost/sso will give 404 page not found error, conflicting with the yunohost login when wordpress is installed on main domian.

The documentation says the following:

The domain chosen during the postinstall is defined as the main domain of the server : this is where the SSO and the web admin interface will be available. The main domain can later be changed through the web admin in Domains > (the domain) > Set default, or with the command line yunohost tools maindomain .

Source: https://yunohost.org/#/domains

The admin login does indeed work with additional domains but the login page for normal users seems to redirect to the default domain. I proved this with yunohost 3.8, I have two domains bound to my yunohost. Just the default domain provides a sso login.

My suggestion for your problem would be to bind another domain to your host and use this one as default domain, so that the domain you want to use for wordpress gets free.

The user login does not take domains into respect. You log in just with your name, not your email.