Previously, in reverse chronological order: URL: IDNA2003, IDNA Hell, URL: IDNA2008, and URL: domain names.
The change to the URL Standard to use Unicode IDNA Compatibility Processing was made a while back. The reasoning is that it provides an interface compatible with IDNA2003, including almost identical processing, but is based on the IDNA2008 dataset. That means that lowercasing still happens. Mapping code points still happens. URLs will remain cool. The URL Standard has the integration details.