Stop pushing SLSA attestations to the registries as OCI referrer tags (attest.yml: push-to-registry: false) and disable buildx's default provenance sidecars (release.yml: provenance: false). GHCR rendered both as package versions / unknown-unknown architecture entries on the package page. The release/publish flow (publish-images gate, RELEASE_TOKEN, web Sentry DSN) is unchanged.
