Bug: Detached nodes are created when portal is rendered conditionally

[kart-c]

I am creating a simple tooltip where tooltip content is rendered in a portal when hovered upon. This creates detached nodes. Added a github test repo and videos of the same.

React version:
"react": "^19.0.0",
"react-dom": "^19.0.0"

Steps To Reproduce

1. Clone the repo. repo link
2. Use TooltipWithoutKey in App.tsx file.
3. Hover multiple times.
4. Take heap snapshot.
5. Detached nodes are noticed.
6. Now use TooltipWithKey in App.tsx file.
7. No detached nodes noticed.

Also tried using the 3rd key argument for createPortal, but it did not work. Which is why the Fragment with key prop was used.

Link to code example: https://github.com/kart-c/react-dom-issue

TooltipWithoutKey

tooltip_without_key.mp4

TooltipWithKey

tooltip_with_key.mp4

The current behavior

Detached nodes are created.

The expected behavior

Detached nodes should not be created.