This is a Qubes issue. This is mostly off-topic here. As per: What to post in this Qubes-Whonix forum and what not.
Qubes-Whonix is only a VMs running on top of Qubes. It conceptually cannot implement a Qubes host operating system anti-forensics feature. Only Qubes developers can add anti-forensics features to Qubes.
On Qubes Disposables wiki page, chapter Warnings, under Amnesic Capability, I just nowe added an updated footnote with ~ 15 references to various Qubes tickets, discussion, documentation.
This is unspecific to Whonix.