There is a new artifact added to compose dependencies i.e. androidx.activity:compose-activity?
setContent has been moved in the recent alpha to the mentioned artifact, but the artifact is not mentioned yet in the list of dependencies in the docs.
Maybe it's not a bug. Seems like navigation that has a Compose component. Likewise, androidx.activity has a Compose component i.e. activity-compose artifact.
However, since it deals with setContent, this should be mentioned in the main Compose docs in the section for declaring dependencies.
There is a mention of activity-compose artifact in the release notes of androidx.compose.ui: