Mounting another app in the setup may trigger a warning

[inottn]

Vue version

3.4.7

Link to minimal reproduction

https://stackblitz.com/edit/vitejs-vite-zttnks?file=src%2FApp.vue

Steps to reproduce

open the link.

What is expected?

No warning.

What is actually happening?

[Vue warn]: Slot "default" invoked outside of the render function: this will not track dependencies used in the slot. Invoke the slot function inside the render function instead. warning is shown.

System Info

No response

Any additional comments?

This issue started to occur from vue 3.4.7, initially reported by vant user(related issue). I speculate that it is related to this commit, and based on the intention of this commit, the cause of this issue should be unexpected.