getDefaultLocale in local/dev different in production

[yassinetrbls]

Hello,

I've added on my blade file:

getDefaultLocale: {{ LaravelLocalization::getDefaultLocale() }}
getCurrentLocale: {{ LaravelLocalization::getCurrentLocale() }}
app.locale: {{ Config::get('app.locale') }}
app.fallback_locale: {{ Config::get('app.fallback_locale') }}

Output local (dev):

getDefaultLocale: fr
getCurrentLocale: fr
app.locale: fr
app.fallback_locale: en

Output production:
getDefaultLocale: en-US
getCurrentLocale: fr
app.locale: fr
app.fallback_locale: en

I don't understand these differences? Configuration file, laravel version, package are the same.

Our routes are inside:
'prefix' => LaravelLocalization::setLocale(),
'middleware' => ['localeSessionRedirect', 'localizationRedirect', 'localeViewPath', 'localize', 'guest']

I've done

php artisan config:clear
php artisan cache:clear

multiple times.

We are hosting our production through Laravel Vapor.

Could you help us?