ludo974 Hi
Uber template is ready for Joomla 4, you can check the Joomla 4 status of all our templates here: https://www.joomlart.com/joomla4-status/
Our template is compatible with both Joomla 3 and Joomla 4 so you can take a FULL BACKUP of your site now and use JA Extensions manager component to update Uber template and all of its complimentary extensions to the latest versions.
And make sure that all other 3rd party extensions on your site (if any) are ready for Joomla 4 as well.
Then follow update steps from Joomla to update your site to Joomla 4: https://docs.joomla.org/Joomla_3.x_to_4.x_Step_by_Step_Migration
Regards