error_reporting defines which errors are reported in the web application and the default value is E_ALL. Prior to PHP 8.0.0, the default value was: E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED. This means diagnostics of level E_NOTICE, E_STRICT and E_DEPRECATED were not shown. There are a number of different settings for this variable and you can change it in the Platform.
Log in to the Platform and select the website from the dashboard and then select either Upgrade PHP Version or PHP & Databases from the side menu.
Scroll down to the PHP Configuration section and click Add Variable. Type error_reporting in the first box and when you click in the Values box you will see the options available. Click Update Configuration to save the changes.