This now seems to be getting errors:
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://tiles.versatiles.org/assets/sprites/sprites@2x.json. (Reason: CORS header ‘Access-Control-Allow-Origin’ missing). Status code: 404.
My guess is that Versatiles have moved things around again and both the fonts and the sprites are now elsewhere.
(for anyone wondering) the underlying OSMF vector tiles are still fine and contain all the data they ever did.