If you read their announcement carefully you'll find things like
All current features are available in both versions
Which strongly implies that the different versions will start to diverge over time. Then at one point they will just be like maah it's not worth putting more work into the open source thing, we'll focus on building new cool features yada yada yada. And this is how all the open to partly open to closed source rug pulls worked in the last years.
(If you want to do this the worst way possible like MinIO you also squash / delete the Git history the moment you announce you're only working on closed source)
