Remember that KG considers 6.5 komi chinese rules then
Territory scoring 6.5 komi will usually have the same winner as either chinese 6.5 or chinese 7.5 depending on who takes the last dame. In this case I guess his move changed that situation (have not looked at the game)
I.e. in chinese counting him filling his own territory would be equivalent to a pass, which would change who gets the last dame if there are still some left
Note that this means that you cannot have KataGo accurately depict the komi on Fox at this moment. If you want to ensure that it plays to win, you would have to make the komi pessimistic from your point of view by setting it to 6.5 when you play as white, and 7.5 when black - you can also try to set it to 7!
I believe Lightvector is considering some support for territory counting, although I don't know the scope of it
