SitecoreIdentityServer in the URL /identity/login/shell/SitecoreIdentityServer is just an identity provider name which is configured in Sitecore.Owin.Authentication.IdentityServer.config. It should be SitecoreIdentityServer for everyone until we change the config manually for some reasons. So basically you no need to worry about redirection to /identity/login/shell/SitecoreIdentityServer when accessing the Sitecore, because Sitecore in-built provider will take care of this and redirect you to the respective identity server.
But you can verify the below items to just make sure that your update is proper.
Verify the Sitecore.Owin.Authentication.IdentityServer.config, you should be having a variable which contains the identity server host details something like the below,
<sc.variable name="identityServerAuthority" value="https://pocsite.identityserver/" />
Update the value if your identity server hosted in a different URL. Also make sure your Sitecore host name is allowed in your identity server, you can confirm this by navigating to the identity server root and verify the below host file
If you don't see your sitecore host name in the above xml file then just add it.