A couple more tips/things to try
Chris_From_Holland wrote:
Thank you for your extended answer and tests.
Knowing this, I'll switch to spot AF next time, and will give a try to your buttons assignment.
Understanding the behaviour is half way managing it. So I know what to try.
Not to mention that the R6 AF is, and stay, a total killer when it comes to precision. The missed are very rare (and I'm kinda torturing it)
A few more things might help.
Set the Magnification to button on reviewing the image on the camera to Actual Size from Selected Point (Menu - Playback (blue) - Tab 4 - Magnification - Actual Size (from selected pt)). If you review a shot on the back of the camera and hit the magnifying glass button, this will zoom in the maximum amount to the center of the focus area. This will let you see if you are locking on focus well quickly.
I like to have my AF points displayed on playback so I can see them in the camera (Menu - Playback (blue) - Tab 5 AF point display. This will let you see where the AF point is on the back display. It would not help in this specific case but it might in others.
Whatever software you are using to covert raw is bad. The noise I'm seeing is horrible for ISO 8,000 on an R6 or R5. What did you use? I would highly recommend downloading a free trial of DxO PureRaw or DxO PL4 and using DeepPrime. You should see a huge difference. The difference is minor at low ISO but it is worth 2 to 3 stops better as the ISO goes above about 3,000. If you want, you can send me the RAW file via private message and I will convert it for you to show the difference.