I have opened an issue in Shortbread for this.
There is no approved usage policy. You can still use the service right now.
It is consuming minutely diffs. We have not yet tweaked caching settings so don’t know how long they will be held in the CDN.
Various style questions
The style the demo page is using is Versatiles Colorful. Style bugs should be reported there. Do not report vector tile issues there. If the tiles produced do not follow the Shortbread Vector Tile Schema 1.0 this should be reported with the definitions. Change suggestions for the Shortbread specification should be reported to its github page.
Errors serving (e.g. 5xx tiles, etc) can be reported here. They might be an issue in Tilekiln, the backend server setup, or the Fastly setup.
I’m not sure what OSM affiliated means in this context. None of the styles of the featured layers on osm.org are controlled by the OSMF or the general OSM community, they are all the responsibility of their maintainers.
One of the servers has stalled in updates and I haven’t yet investigated. The monitoring (not yet enabled) would have shown this.