I think it does in some cases, like if you buy a System 76 computer with PopOS, or you buy a server with Red Hat.
However if you install a Linux OS yourself, that is available free of charge, there isn’t any money to claim back, and it would be illogical if there should be demands on updates.

I think logically there needs to be money involved, so if you download PopOS you’re on your own, but if you bought a computer with PopOS installed it is part of a package.

I’m not a lawyer, but from my experience this is how things typically work.