With SSPL, MongoDB does not let Cloud providers like Microsoft, Amazon, Google etc - run a fork of opensource MongoDB and sell it as a PaaS service where they will earn revenue but MongoDB will get nothing. From MongoDB's perspective it is fair only if the cloud providers open up their management platform code as well. And that of course is the core of cloud IP. It will not happen.
But you can still install Opensource MongoDB on a VM in cloud, run your applications and use cases (knowing that the opensource version is not as secured as enterprise version). Nothing stops you from doing that.