More and more projects are using the Sustainable Use License: Code search results · GitHub
As the author of the license, could you please submit an SPDX identifier for it (e.g. SUL-1.0)? It’s as simples as sending a Pull Request to https://github.com/spdx/license-list-XML.
This will allow projects using SUL to be displayed with the correct notice on places such as flathub.
Thank you! 