This should prevent bugs like #17165 where a naked reference to window will crash if used in a SSR context where there's no window.

See more details in the comment from @jsnajdr #17165 (comment):

In this case, the easiest TDD-style test would be to simply import @wordpress/compose in a Node.js environment without DOM. And it would fail.

Neither compose nor components packages use the sideEffects: false flag (although they would be a good fit IMO), so using anything from compose bundles the whole library.

And the window check is a top-level statement in the module. We don't need to use or instantiate the useReducedMotion hook at all to get a broken build.