The brief
Tailwind CSS 4.3.4 adds @tailwindcss/turbopack, a loader for using Tailwind with Next.js through Turbopack. The release note presents this as a new package rather than a change to every Tailwind installation. Teams using the Next.js development server can check the upstream package and the release notes before changing their build setup. The same release includes a watch-mode fix for symlinked @source files whose real paths were not otherwise scanned.
Several fixes concern CSS @scope handling. Generated utilities are wrapped by the scope instead of incorrectly nested inside it; nested scopes keep their semantics when flattened; and declarations directly inside a scope are preserved through :where(:scope). These are narrower parser and output fixes than the new loader, but they matter to projects using scoped styles. The source release lists the individual issues and links to each change for teams checking whether a bug affects their CSS.