Download the Testers-Only version of Whonix for VirtualBox:
Alternatively, in-place release upgrade is possible upgrade using Whonix testers repository.
Same as Whonix VirtualBox 18.104.22.168.6 - Testers Wanted! - Stronger Linux User Account Isolation and more Hardening but bugs reported there fixed.
This release would not have been possible without the numerous supporters of Whonix!