When you start the upgrade to Moodle 4, you will see this messasge in the Enviroment check:
It has been detected that the XML-RPC Web Service protocol is enabled on your site. This feature relies on the PHP XML-RPC extension which is no longer maintained by PHP.
This is shown because you have the XMLRPC protocol enabled for Joomdle to work. In PHP 8, XML-RPC is not available.
With Joomdle 2, you can use REST web service instead, so XML-RPC is not needed.
- In Joomdle configuration in Moodle, set Web services protocol to REST.
- In Joomdle configuration in Joomla, set Web services to REST
- Go to Moodle->Site Administration->Server->Web Services->Manage protocols and disable XML-RPC protocol
- In Joomla backend, go to System check page in Joomdle to make sure everything keeps working as expected