During testing the fix to the white screen error was a part of two bugs, of which
this post explains how to patch the bug (a script in the admin pages was corrupting cookies in PHP8 which resulted in a white a page when you try to hit the landing page as the corrupt cookie would cause the dashboard.php page to not load).
You should still be able to access the other pages in the Control Panel such as primary.php or features.php to manage the forum if this bug is unpatched.
As for your support inquiry in your other thread, please keep the discussion in one place
here.
