When unknown is set to polyfill and the bundle being returned is for an unknown browser, the bundle will wrap all polyfills in feature detects.
The default value for unknown is no longer ignore, it is now polyfill.
The version of the polyfill-library can be chosen with the version parameter. The default value is latest. If you want to use the polyfill-library that was used in v2, set version to 3.25.1.
The libVersion parameter is no longer supported. We no longer support using an older version of the polyfill collection with the current version of the service. To use an older polyfill library, use the version of the project that contains the library in the state you want it (not possible if using cdn.polyfill.io/v2)
The gated parameter is no longer supported. Use flags instead.