Yes it is. It plainly meets all the criteria in the definition iff AGPL meets them too.
* https://web.archive.org/web/20230411163802/https://lists.ope...
* https://opensource.org/blog/the-sspl-is-not-an-open-source-l...
* https://en.wikipedia.org/w/index.php?title=Server_Side_Publi...