Composite unique field validation rule only returns error message for the last field being evaluated

[lasseeee]

• Laravel Version: 7.28.3
• PHP Version: 7.4.7
• Database Driver & Version: MySQL 5.7.25

Description:

When creation a form request object with a composite unique validation rules like this:

'name' => [
    Rule::unique('participants')->where(function ($query) {
        $query->where('country_code', $this->country_code),
    }),
],

'country_code' => [
    Rule::unique('participants')->where(function ($query) {
        $query->where('name', $this->name)
    }),
],

and with corresponding form fields, the validation error message only shows for the last field in the validation list, country_code in this case. It should really display the unique validation error message for all the fields in the form, when they are attached to the fields using $errors->first('field_name'), not only the last one being evaluated, or is this intended behaviour for the unique validation rule?

I could also upgrade the project to Laravel 8 just to check for changes, if that makes your life easier, Dries?

Steps To Reproduce:

Create a form object like the one above with corresponding form fields, add per-field validation messages and submit the form.

[lasseeee]

Also the case for laravel 5 #34441

[lasseeee]

Dupliate of #34462