Probably the problem is you’re using App\FunAuxiliar.php, instead of app\FunAuxiliar.php.
To my knowledge, in Laravel, the default application folder is app and not App.
On operating systems like Windows, it makes no difference. But on Linux it does, since Linux is case-sensitive (case-sensitive).
This problem often happens when you program your application on Windows and move it up to a Linux server.
Therefore, the recommendation is always to reference the actual folders as their value is, and not to change a case (upper or lower case) of a letter of the directory name, as you did.
What is the operating system of your Production server?
– Wallace Maxters
Is the server linux? Remember that it is case sensitive and if Voce is searching with minuscula will not find
– Ademilson Santana da Silva