[React 19] Upgrading React causes infinite refetching

[cometkim]

Summary

The reproduction is using Relay, but I came as this seems closer to a bug in React than Relay.

https://stackblitz.com/@cometkim/collections/react-relay-suspend-loop

With this basic setup, using useLazyLoadQuery with network-only to make a new fetch() call on render. The code works fine in v18, but after upgrading to v19, it starts remounting an element infinitely.

• React v18: No issues
• React v19: No differences, but the children including the suspense boundary is unexpectedly unmounted, resulting in an infinite refetch loop.
• React v19 workaround 1: Removing <StrictMode> seems to solve the issue.
• React v19 workaround 2: Wrap the parent (which is just a context provider with nothing special) by one more <Suspense> boundary. It seems to do not make sense, but it works.

The expected behavior is that the <Suspense> boundary is retained stable, and the <NetworkOnly> is rendered after waiting for the QueryResource fulfilled.

However, this seems to me like the <Suspense> could suspend itself.

[Kanishk-tiwari-045]

So for starters, I would just like to ask, what exactly you are looking to resolve this? Like for say, we can stay on the v18. Is upgradation so much important ?

[nkalpakis21]

built an app to get paid for this PR https://www.n0va-io.com/discover/facebook/react