Make it clearer that you need Akeeba Backup 9 on Joomla 4. When you upgrade a Joomla 3 site to Joomla 4 you will be told to install Akeeba Backup 9. Not doing so will result in a perpetual compatibility warning which is displayed in the Control Panel, the Backup Now page and reported as a warning on each and every backup. Once you install Akeeba Backup 9 you will no longer be able to use Akeeba Backup 8, only migrate from it (if you really want to, you can use it AT YOUR OWN RISK which means with zero support from us). In this case you will be reminded to complete the migration and you will be given instructions on removing Akeeba Backup 8 from your site.
Bug fixes and minor improvements. Please take a look at the CHANGELOG below.
Do not use Akeeba Backup 8 to take backups of Joomla 4 sites. Akeeba Backup 8 is minimally compatible with Joomla 4, as in: it won't break your site when you upgrade from Joomla 3.10 to Joomla 4. The minimal compatibility is there only for the purpose of facilitating the upgrade process from 3.10 to 4.x. You cannot even install Akeeba Backup 8 on Joomla 4.1 and later — this is deliberate, there's no need for you to do that. Once you install Joomla 4 you MUST install Akeeba Backup 9 and complete the migration process to it, then uninstall Akeeba Backup 8 per the messages which will be displayed on Akeeba Backup's Control Panel page. Please note that we do not provide any support for taking or restoring backups of Joomla 4 sites with Akeeba Backup 8 after February 17th, 2022.
Please consult our Compatibility page. It explains our version support policy and lists which versions of our software are compatible with which versions of Joomla and PHP.