[BUG] Artifact Streaming on AKS nodepools appears to intercept external registry pulls via localhost:8578 internal proxy

Artifact Streaming is enabled on our AKS worker node pools. We observed image pull failures for external registry images, for example images hosted in GCR / Artifact Registry.

Error seen in pod events:
unexpected status from HEAD request to http://localhost:8578/v2/.../manifests/...?...: 503 Service Unavailable

What we observed:
- The image is hosted in an external registry, not ACR.
- The image pull appears to be going through the localhost:8578 artifact streaming path, where it fails with 503 Service Unavailable and the pod doesn't come up.
- Microsoft docs confirm localhost:8578 is part of the artifact streaming path, but we could not find documentation describing how external registry images should behave on streaming-enabled node pools

Question:
Is it expected that external registry pulls are first routed through the local artifact streaming endpoint on AKS nodes, or should non-ACR images bypass artifact streaming entirely?