Is it possible to login from multiple urls?

In the Changelog for 5.1.0 it is stated:

The support for X-FORWARDED-* headers has been removed because it was possible to solve it with the mandatory urls:baseUrls setting in an easier way.

I can’t find documentation about the use of this setting - just in singular (urls:baseUrl). Is it possible to provide a set of urls in order to login from different urls? The context is that we have a different url for each app - and it would’ve been nice if customers could use their own app url for the SquidEx login.

Right now it is not possible. I have also reverted this change again, but even with this change it is not possible because the identity server has to know all valid URLs upfront, which is the main reason for the urls:baseUrl setting.