I seem to recall during one of the Whonix upgrades I received a message about how Tor Browser’s security level settings by default would be set to safest when opening. This is different from the default settings for Tor Browser. Was this a change initiated by Whonix?
Just to add, I am now running the 220.127.116.11.6 tester version in KVM, but before I installed it, I was using an older, but updated version of Whonix 15 and I was seeing the same issue. I have noticed this for about a week or two recently. Definitely a security concern.
Then please try to reproduce this in on a plain Debian VM. Such as a Debian buster VM.
Non-Whonix. I.e. outside of Whonix. If the bug is reproducible there too, it should be reported to The Tor Project.