Hi there - I have a nextjs app I'm moving over to use turborepo. We use the pages router, but use next/navigation over next/router for if/when we navigate over to the app router.

In our regular monolith, building works, no problem. Since I've moved everything over, I am getting the following littered throghout our build logs (and seemingly causing it to fail?):

│ Error occurred prerendering page "/callback/something". Read more: https://nextjs.org/docs/messages/prerender-error
│ Error: invariant expected app router to be mounted
│     at useRouter (/myproject/apps/web/.next/server/chunks/4916.js:1287:37)
│     at useSkewProtection (/myproject/apps/web/.next/server/chunks/2974.js:2102:78)
│     at MyApp (/myproject/apps/web/.next/server/chunks/2974.js:1388:101)
│     at renderWithHooks (/myproject/node_modules/react-dom/cjs/react-dom-server.browser.development.js:5658:16)
│     at renderIndeterminateComponent (/myproject/node_modules/react-dom/cjs/react-dom-server.browser.development.js:5
│ 732:15)
│     at renderElement (/myproject/node_modules/react-dom/cjs/react-dom-server.browser.development.js:5957:7)
│     at renderNodeDestructiveImpl (/myproject/node_modules/react-dom/cjs/react-dom-server.browser.development.js:6115
│ :11)
│     at renderNodeDestructive (/myproject/node_modules/react-dom/cjs/react-dom-server.browser.development.js:6087:14)
│     at renderIndeterminateComponent (/myproject/node_modules/react-dom/cjs/react-dom-server.browser.development.js:5
│ 786:7)
│     at renderElement (/myproject/node_modules/react-dom/cjs/react-dom-server.browser.development.js:5957:7)
│ Export encountered an error on /404, exiting the build.

Has anyone seen this before, or know what might be happening? To be clear, we are not using app router in any way, and have never had issues with next/navigation in pages router historically.