use cache Directive in Next.js 15 Canary Fails to Persist Cache and Deduplicate Requests Reliably

[TheKing0000]

Summary

I'm using the new "use cache" directive in Next.js 15 (latest canary) along with cacheLife("hours") in my server functions. However, I've noticed that caching does not behave as expected:

Cached responses are frequently missed, resulting in repeated API calls for the same request.

Deduplication often fails — I see the same API call hitting my backend multiple times simultaneously.

This occurs even though all related server functions are using the "use cache" directive with a defined cache lifetime.

This behavior results in unnecessary API usage and breaks the expected cache efficiency.

Additional information

No response

Example

No response

[kachkaev]

Relevant discussion (with reproduction steps): #71896