I would solve that by using the redirectTo() method in the Login Controller and checking which route is sending the request through the path() method. You have to name the routes for it to work though. So in your login Controller you'll have this;
use Illuminate\Support\Facades\Route;
protected function redirectTo(){
if(Route::currentRouteName() == 'login'){
return '/';
}else if(Route::currentRouteName() == 'checkout'){
return '/checkout';
}
}
more info on how to get the route name here
and info on the redirectTo() function here
Try it out, tell me what happens..