I also have error with BuddyPress:
WordPress version 6.0.1
Active theme: OneCommunity Child Theme (version )
BuddyPress (version 10.3.0)
PHP version 8.1.0
Uncaught Error: Class "BP_Admin" not found in ..../wp-content/plugins/buddypress/bp-core/bp-core-admin.php:20
It works ok, if I set PHP to 7.4 version.
Site works ok with PHP 8.1.0 if i disable BuddyPress plugin.
