Unexpected weatherKit REST API changes and slow response times

We have been testing and evaluating the WeatherKit REST API. We recognize that the API is currently marked as BETA in the documentation.

There are a few issues we have noticed that makes us a bit concerned to make the full switch from DarSky:

1. Sometime last week, the API changed (undocumented) so that while only providing hourlyEnd makes the API respond with HTTP 404, the fix for this seems to be explicitly providing the hourlyStart parameter. Can we expect more changes like this up until the removal of DarkSky, or perhaps more importantly afterwards.
2. Response times are mostly slower than when compared to DarSky, from our measurements, the P50 for WeatherKit is about 240ms, as compared to 330ms, but everything over P70 is slower with P95 almost double response time for WeatherKit.
3. We are seeing intermittent HTTP 502 and HTTP 504 responses for seemingly random requests at an approximate rate of 0.4%. We have been unable to discern an potential reason for these errors.

We would like to find clarity about what we can expect in terms of quality of service for the API in the near future and especially up until the end of March when DarkSky will disappear as well as in the future.