Page displays 'index.php'

www.[mywebsite]/public/index.php - shows index.php as text string
www.[mywebsite]/public/ - shows index.php as string

I don't understand why you see index.php as text string.
It seems you have something incorrect settings in Apache's configuration.

If you navigate to http://localhost:8080/public/, you should see:
404
Can't find a route for 'get: public/'.

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper