There seems to be a mixup of version numbering in the latest download release of Akeeba Backup for Joomla 4. It's called 7.6.0, when it should have been 9.x something. Probably a mix-up with the Wordpress version, which is at 7.6.0 right now.
After installing "7.6.0" on Joomla 4, the previous version 9.0.11 is displayed as an update in Joomla Updater.
All this is extra confusing since you have both the 8.x-series for Joomla 3, and the 9.x-series for Joomla 4. Please look into this.