I'm really sad that tree-specific context for server components seems to be an afterthought. As the Twitter thread suggests, if you have something that can be used across all the server components for an entire request, you can use the cache functionality or rely on Next's URL parameters. But if you've relied on Context as a way to let deeply nested components access some kind of business logic that's specific to only a part of a rendered page, and if you want/need those components to be server components, you'll need to switch to explicitly drilling the props through.
For CSS-in-JS, those are all 3rd party libraries, so they need to adapt on their side. For example, `styled-components` uses Context heavily, so they need to re-think their approach. For `css-modules` adapting to Server components looks doable, but requires substantial amount of work.
Context is a really nice way to do this.