Environment

Newly installed Joomla 6.0.0

How To Test

Go to System Dashboard - Manage - Plugins.
Check the status of the plugin 'Behaviour - Backward Compatibility 6' and make sure it is enabled.
Go to System Dashboard - Information - System Information.
Check the setting 'Joomla Backward Compatibility Plugin'.

Expected Result

Enabled

Actual Result

Disabled

Resolution

Line 317 of administrator/components/com_admin/src/Model/SysinfoModel.php in Joomla 6.0.0 is identical in Joomla 5.4.0:

       'compatpluginenabled'    => PluginHelper::isEnabled('behaviour', 'compat'),

Change the folder from compat to compat6:

       'compatpluginenabled'    => PluginHelper::isEnabled('behaviour', 'compat6'),

Report

First reported by @gws in the Joomla! Forum topic backwards compatability plugin