It stores its configuration in the database. It means that I can't just configure it in some yaml configmaps. There's no easy supported way to test some changes on test server and then move those changes to production. You need to click around in its UI and you better do it well, it's a security tool after all.
There's adorsys/keycloak-config-cli which is third-party solution which is supposed to somewhat mitigate this issue (you supply a config and it'll try to adjust keycloak instance to this config), but it's absolutely not first-party solution and does not work as well.
Please just store users in the database. Let me specify everything in config yamls, so I can change it and restart the server and that's about it. That's how gitops is supposed to work.