The default Keycloak distribution is now based on Quarkus, which brings a number of breaking changes configuring Keycloak and deploying custom providers. The new distribution tends to be faster, leaner, and easier to configure.
Migrating from the WildFly-based distribution is not going to be straightforward for everyone, since how you start and configure Keycloak has radically changed. With that in mind the project will continue to support the WildFly distribution until June 2022.
Some new features:
For details have a look at https://www.keycloak.org/2022/02/keycloak-1700-released.html