I suspect it's not just this, there's plenty of 'optimization' around rubberbanding usage limits as well as routing to a different model in the backend. The incentives are too strong.

I've been using the API (shameless plug: via alyph.ai) and the difference is crazy.

The chat-based models are obviously being lobotomized based on personal usage and general load (e.g. PST business hours are worst).

API doesn't seem to be affected by this.