All you get is a watermark in the corner

Well, that is a consequence. Just not a very big one. You also cannot change the background in the settings, though that is also a very small consequence. Yeah, they are only small and you can likely live with them, but small and tolerable are not zero.

there will be a subscription “premium” version like in any app that removes ads and enables AI features.

This makes me glad I no longer use it. An OS should not have ads baked into its core and there should not be a subscription for it.