I found the interview [1].
TL;DR they don’t change the weights, but they sometimes run A/B tests and modify the system prompt. The underlying model is very sensitive to changes. Even a small change can have broad impacts.
[1]: https://lexfridman.com/dario-amodei-transcript#chapter8_crit...
I hope you get it figured out!
One thing that has helped me when I can’t quickly get to the expected result is using the Anthropic prompt generator in the dev console.
This isn’t a critique of your prompt—it’s likely solid since you use the system frequently. However, for troubleshooting, the prompt generator can be useful because it creates very long and specific prompts. You can compare the results from your prompt to the ones generated to see where there might be differences.