This upgrade is designed to be fully backwards-compatible. Any icon names which have changed will be automatically remapped to the new name. For now, this will happen silently. In future, once core & official themes/plugins have been updated, we will start raising deprecation errors to help theme/plugin authors update their code.
Extracted from https://github.com/discourse/discourse/pull/28715
Announcement at https://meta.discourse.org/t/were-upgrading-our-icons-to-font-awesome-6/325349
Co-authored-by: awesomerobot <kris.aubuchon@discourse.org>
David Taylor