According to the company: mongodb.com/…/mongodb-issues-new-server-side-publ…

Unfortunately, once an open source project becomes interesting, it is too easy for cloud vendors who have not developed the software to capture all of the value while contributing little back to the community

They are totally morally correct imo, but reality simply doesnt work like that.

“We have invested approximately $300M in R&D over the past decade to offer a modern, general purpose, open source database for everyone. With the added protection of the SSPL, we can continue to invest in R&D and further drive innovation and value for the community.”

They also just spent a bit too much money on a single project from what it look like.