chore: comment

Co-authored-by: 翠 / green <[email protected]>

packages/vite/src/node/plugins/css.ts

@@ -2376,6 +2376,11 @@ const makeModernScssWorker = (
             const resolved = await internalCanonicalize(url, importer)
             if (
               resolved &&
+              // only limit to these extensions because:
+              // - for the `@import`/`@use`s written in file loaded by `load` function,
+              //   the `canonicalize` function of that `importer` is called first
+              // - the `load` function of an importer is only called for the importer
+              //   that returned a non-null result from its `canonicalize` function
               (resolved.endsWith('.css') ||
                 resolved.endsWith('.scss') ||
                 resolved.endsWith('.sass'))