Well I don't want to be too positive, but upgraded both my Z6 II and Z7 II yesterday to the new firmware V1.4,and did some testing with the dogs outside. Previously I would never ever use auto area AF as it never worked and the failure to focus rate was abysmal, however it really surprised my last night. On both cameras, with Auto Area AF and "Cats and dogs AI" selected, at over 10m away, the camera picked up the eyes on both dogs (and they are both black so very low contrast), and set to drive mode H+ silent, 12 bit raw, when they trotted towards me, I was most surprised to see the AF box tracking the dogs faces and when I checked the images later, nearly 50% of them were tack sharp, with another say 30% slightly soft and just 20% totally OOF. that compares to about 5% before the upgrade.
Whilst that result is totally unscientific I know and it doesn't make either cameras Z9 (or my new Olympus OM-1) AF performance, it is most definitely quite marked how much of an improvement this "minor" upgraded is. The same was true when set to Auto Area AF and human face eye detect, where in the AF point hit and tracked the target much more tenaciously that it ever did before. Overall, quite happy with this "minor" upgrade.