[compat] model configuration doesn't support modelValue as a prop value

[CyberAP]

Version

3.1.0-beta.3

Reproduction link

https://codesandbox.io/s/frosty-haze-zb9lx?file=/src/Child.vue

Steps to reproduce

1. Create a component with a model config that supports v-model directive
2. Define model config prop value as modelValue
3. Use that component with a v-model directive in a parent component

What is expected?

A prop option should be used to pass model value from parent to child component on a correct prop

What is actually happening?

No model value is passed to the child component

If a prop model config value is changed to any other value it works back again: https://codesandbox.io/s/upbeat-tdd-jypn0?file=/src/Child.vue

A workaround is just to switch to Vue 3 mode.