If you are using a mail service provider like SendGrid, it can create a proxy that may cause issues when you try to validate emails, for example.
To fix this, go to your bootstrap app file and add this line to the middleware:
$middleware->trustProxies(at: '*');
Then it should look like this:
// bootstrap/app.php
<?php
use Illuminate\Foundation\Application;
use Illuminate\Foundation\Configuration\Exceptions;
use Illuminate\Foundation\Configuration\Middleware;
return Application::configure(basePath: dirname(__DIR__))
->withRouting(
web: __DIR__.'/../routes/web.php',
commands: __DIR__.'/../routes/console.php', health: '/up',
)
->withMiddleware(function (Middleware $middleware) {
$middleware->trustProxies(at: '*');
})
->withExceptions(function (Exceptions $exceptions) { //
})
->create();