Issue with allowComposition

[kefniark]

Reporting a bug?

After upgrading to 9.2.2, I'm getting some errors on a vue2 project moved to vue3 and composition api (done at ~80%). We are rewriting components but its a big project and there are still few $t and $tc in templates that we cant instantly replace and use legacy: false

The setup is really similar to the documentation one, just using the recent allowComposition flag

  const i18n = createI18n({
    allowComposition: true,
    locale: 'ja',
    fallbackLocale: ['en'],
    messages
  })

It mostly work and I can see my contents, but the problem is during initialization

import { useI18n } from 'vue-i18n'

const i18n = useI18n()
console.log(i18n.locale.value)

watch(() => i18n.locale.value, (locale) => {
  console.log(locale)
})

returns me

en-US <--- this is wrong ja

so sometimes, I get some operation like API call done with the wrong locale ... with a value not even in my list of locales. and later vue-18n set the right value but it could be too late already.

Expected behavior

If I stop using this allowComposition flag, this issue seem to disappear and I get the right value directly

// allowComposition: true,
legacy: false,

ja

No en-US locale for a short amount of time.

Reproduction

https://codesandbox.io/s/adoring-banach-5lbyld?file=/src/main.js

System Info

System:
    OS: Windows 10 10.0.19044
    CPU: (12) x64 Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz    
    Memory: 3.22 GB / 31.94 GB
  Binaries:
    Node: 18.4.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.19 - C:\Program Files\nodejs\yarn.CMD
    npm: 8.12.1 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Chrome: 105.0.5195.102
    Edge: Spartan (44.19041.1266.0), Chromium (105.0.1343.33)
    Internet Explorer: 11.0.19041.1566
  npmPackages:
    @vitejs/plugin-vue: ^3.0.0 => 3.1.0 
    vite: ^3.0.0 => 3.1.0 
    vitest: ^0.9.0 => 0.9.4 
    vue-tsc: 0.33.9 => 0.33.9

Screenshot

Additional context

No response

Validations

• [X] Read the Contributing Guidelines
• [X] Read the Documentation
• [X] Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• [X] Check that this is a concrete bug. For Q&A open a GitHub Discussion
• [X] The provided reproduction is a minimal reproducible example of the bug.