Environment

• Operating System: Linux
• Node Version: v22.13.1
• Nuxt Version: 3.17.4
• CLI Version: 3.25.1
• Nitro Version: 2.11.12
• Package Manager: npm@10.9.2
• Builder: -
• User Config: devtools, colorMode, compatibilityDate, experimental, routeRules, app, icon, modules, fonts, image, tailwindcss, gtm, router, components, srcDir, schemaOrg, runtimeConfig, build, nitro, vite, headlessui, imports, $production
• Runtime Modules: ./src/modules/logger/module, ./src/modules/error-pages/module, floating-vue/nuxt@5.2.2, @nuxtjs/eslint-module@4.1.0, nuxt-headlessui@1.1.4, @vueuse/nuxt@10.9.0, nuxt-esi-tags@1.0.8, @nuxt/test-utils/module@3.14.2, radix-vue/nuxt@1.9.14, @nuxt/ui@2.21.0, nuxt-auth-utils@0.5.15, @zadigetvoltaire/nuxt-gtm@0.0.13, @nuxt/image@1.8.0, nuxt-schema-org@3.5.0, @nuxt/fonts@0.10.3
• Build Modules: -

Reproduction

https://stackblitz.com/edit/github-9xvsdsz9?file=pages%2F%5B...layout%5D%2Fpage-%5Bpage%5D.vue

I think it can be easily reproduced by having the following folder structure in /app/pages/ :
pages/
├── [...layout].vue
├── [...layout]/
│ ├── index.vue
│ └── page-[page].vue

Describe the bug

TL;DR With this PR a bug was introduced, and nested catch-all routes are no logger properly grouped as children.

After upgrading from Nuxt 3.15.4 to 3.17.5, nested catch-all routes are no longer being grouped as children but are instead being flattened into separate top-level routes, breaking our existing URL structure.

I went in to more details here and here.

Let me know if you need more info.

Additional context

No response

Logs