[j-f1]

There were security vulnerabilities a while ago that resulted from people being able to upload React-element-shaped JSON objects in certain places strings were supposed to go. IIRC this allowed for XSS, so React added a special symbol (the $$typeof key) that would have to be imported somehow in order to add it to the plain objects.

[steadicat]

Interesting. Why not make that special symbol a tiny NPM module with a single published version that any library wishing to support JSX can import?