NextJS 15's `next/font` breaks alternate header injection.

[zenzen-sol]

Description

I notice that in the NextJS 15 release candidate, the "alternate" links that should appear in the response header are missing if next/font is used to optimize fonts. I'm not sure whether this issue belongs to NextJS or next-intl.

Verifications

• [X] I've verified that the problem I'm experiencing isn't covered in the docs.
• [X] I've searched for similar, existing issues on GitHub and Stack Overflow.
• [X] I've compared my app to a working example to look for differences.

Mandatory reproduction URL

https://github.com/zenzen-sol/next-reproduction-template/tree/sol/repro-001-next-15-broken

Reproduction description

Steps to reproduce:

1. Open reproduction
2. Run pnpm run dev
3. Reload http://localhost:3000 in a browser.
4. Check the response header links in dev tools.

✅ OK(Next 14): https://github.com/zenzen-sol/next-reproduction-template/tree/sol/repro-001-Next-14-working

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🙅🏻Broken (Next 15rc + next/font): https://github.com/zenzen-sol/next-reproduction-template/tree/sol/repro-001-next-15-broken

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✅ OK (Next 15rc without next/font): https://github.com/zenzen-sol/next-reproduction-template/tree/sol/repro-001-next-15-working

Expected behaviour

Both the next-intl and next/font links should be present in the response header.