Ask HN: Claude Sonnet 4 API returning model with April 2024 knowledge cutoff

Testing the claude-sonnet-4-20250514 endpoint, I'm getting a model that identifies as Claude 3.5 Sonnet with April 2024 knowledge cutoff. It doesn't know about 2024 election results or events after April 2024.

Reproducible test: https://console.anthropic.com/workbench/56d29701-4dc0-4789-a9b8-0935032b44b7

Anyone else experiencing this? More importantly, what could cause this technically? Model routing issue? A/B testing? Gradual rollout?

Looking for technical explanations more than complaints. My app depends on Sonnet 4's capabilities and this is causing issues.