Bug: React 19 - Suspense Siblings Fall Back to Sequential Loading Under Load

[dkempner]

Describe the bug

Cross post from an issue in react:
facebook/react#33503

Your minimal, reproducible example

codesandbox.io

Steps to reproduce

1. Open the app in a new tab (Example link for @tankstack/react-query)

2. Open network tools and refresh the page
3. Notice that the requests to dummyjson are made in parallel

4. Visit the performance tab in chrome devtools and apply 20x slowdown

5. Refresh the page
6. Notice that the requests to dummyjson are made in sequence

Expected behavior

In a challenging performance situation, Suspense siblings initialize as a waterfall instead of concurrently.

How often does this bug happen?

None

Screenshots or Videos

No response

Platform

Mac on Chrome

Tanstack Query adapter

None

TanStack Query version

5.80.6

TypeScript version

No response

Additional context

No response

[dkempner]

I described the issue incorrectly. This is not a real bug.