Elasticsearch 9.2.1 snapshot visible in repository but restore fails with snapshot_missing_exception

Yep that'd do it. This will destroy your repository contents. See these docs:

You may use an S3 Lifecycle Policy to adjust the storage class of existing objects in your repository, but you must not transition objects to an unsupported class such as the Glacier classes, and you must not expire objects. If you use a Glacier storage class, or another unsupported storage class, or object expiry, then you may permanently lose access to your repository contents.