Providers publish retirement dates. They do not tell you what changes in your prompts. We run yours against both models and measure the difference against your endpoint's own normal variation. Free, no signup, results in a few minutes.
We compute Cliff's delta between the model-to-model differences and the model-to-itself differences. A high-temperature endpoint that disagrees with itself constantly needs a large gap to register; a deterministic one registers a small one. Thresholds were fixed in writing before any data was collected.