I was under the impression that 1.0 would remain backwards compatible with API v3.
The following API v3 endpoints are not functioning:
/api/v3/federated_instances(some apps require this to know how to handle certain links)/api/v3/user(anything profile related)/api/v3/community(create community)/api/v3/modlog
Works but with Issues:
/api/v3/search: Search works but at minimum the search type is not honored. e.g. Scope to users returned posts and comments as well.