Login to your site cPanel or use FTP. Go to the public_html folder of your website. Edit the index.php file and change the environment from production to development at line number 57.
define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'production');
If you want to see database related errors. Go to the application/config folder and edit the database.php file. Change the db_debug to true at line number 84.
'db_debug' => true,
Note: After troubleshooing, do not forget to roll back the files to their original for security reasons. Set the environment to production and db_debug to false.
Google Maps is no longer free. You have to associate a credit card so that you can get billed if your site has requests that exceed the $200 credit they give you monthly for free. That is why you get the watermarked maps.
For more information, see: https://cloud.google.com/maps-platform/pricing/
If you want to use map free like earlier, then create an account with valid details (billing, payment, etc.) google gives $200 MONTHLY CREDIT Which is EQUIVALENT To FREE USAGE