If you pay attention they state it's a parry you need to perform at the last possible moment which leaves the enemy open to a one hit kill, so it more of Sekiro than AC.
Floaty is a complaint i never understood personally, it's like every game must feel the same, i remember people calling Sly that, and the Sly games are some of THEM most fun games out there.
Dude have you ever played the first ac games? You literally have enemies that take turn to attack just to be blasted by a one hit kill counter, exactly like you see in taushima gameplay.
In sekiro you have to parry multiple times to increase an indicator and only after that you can make a fatality move, it is more similar to ac1 or brotherhood than sekiro, in the from game only when you are upgraded you can instakill minor enemies with one single parry but that is like 10% of the total encounters in that game and not really how the combat work most of the time.
And we will see how tight is the parry window on this one, if you watch the standoff were he kill 3 enemies he make the parry when they still have their arm on the air and not when the blade is almost touching you, it looks very forgiving, and it's only natural, they said multiple times that the game is not gonna be sekiro level of difficulty and they have to sell to the masses of casuals out there, exactly like ac saga, no room for ultra technical and hard combat ala sekiro.
And being floaty is a legitimate critique, not everyone loves that feeling and that's why you never gonna see ac origins or odissey cited in any poll about the best combat systems of this gen, they are serviceable at best, floaty, clunky, poorly animated etc.
Sly is beloved yes, but ask to yourself, is combat the most important mechanic in a game like sly cooper or maybe the combat being floaty and serviceable is not really a great flaw in a game like this?
Many games have reactive and gamey but still heavy and satisfying to watch combat system, ac saga was never ever a saga with great combat, it was piss easy counter de dios based in the first games and clunky floaty dars soul-ish in the last 2 games