Accessing element.ref was removed in React 19. ref is now a regular prop. It will be removed from the JSX Element type in a future release.

Component Stack: 

SingleObserver index.js:10
    ResizeObserver2  index.js:12
    div  unknown:0
    RawList  List.js:32
    NodeList  NodeList.js:74
    div  unknown:0
    Tree2 Tree.js:33
...

Looks like this is a problem with React 19.

We use React 19 and Typescript with "rc-tree": "^5.13.1"