Whonix does not produce Tor Browser. The Tor Project does. And Whonix did not make any changes related to that.
Therefore to have a chance of seeing this fixed, this issue must be reproduced outside of Whonix. Meaning, without Whonix involved. A Debian busted based VM would be good. And then the issue needs to be reported on the Tor Project issue tracker.
As per Free Support for Whonix ™.