From
https://spring.io/blog/2019/11/14/spring-security-oauth-2-0-roadmap-update
In 2019, there are plenty of both commercial and open-source authorization servers available. Thus, the Spring Security team has decided to no longer provide support for authorization servers.
UPDATE: We’d like to thank everyone for your feedback on the decision to not support Authorization Server. Due to this feedback and some internal discussions, we are taking another look at this decision. We’ll notify the community on any progress.
Basically spring drop support for auth servers since there is a lot of good service already working,not need to reinvent the whel. But they are rethinking it, I imagine it is to give more scope to sprig framework