Looking at https://webassets.mongodb.com/_com_assets/legal/SSPL-compare... and in particular section 13, this is an attempt to squash a cloud service from packaging MongoDB and their own custom backup and UI software without offering the backup and UI software also under the license.
> MongoDB is a bit miffed that some cloud providers — especially in Asia — are taking its open-source code and offering a hosted commercial version of its database to their users without playing by the open-source rules.
> So while the SSPL isn’t all that different from the GNU GPLv3, with all the usual freedoms to use, modify and redistribute the code (and virtually the same language), the SSPL explicitly states that anybody who wants to offer MongoDB as a service — or really any other software that uses this license — needs to either get a commercial license or open source the service to give back the community.
If I was to write blog software that is backed by MongoDB, that blog software doesn't have to be released under the SSPL.
That said, the license and its application to patches on older versions would raise some eyebrows in legal with (likely valid) concerns that an upgrade of a point release may change the license on them as it was done before. In the interest of minimizing risk for the organization, the license and the company that changes its license so easily would be ones that would get extra scrutiny and developers using it would likely be advised to ask permission rather than forgiveness when dealing with it (rather than the other way around) as the risk to the org is greater than accidentally incorporating some GPL code in a service.
