+1bill shoe wrote: I can think of two possibilities.
One. There is a tiny slot (disconnection) between the red horizontal-ish fin just in front of the tire and the black vertical fin just inboard of it. Maybe we just don't see it. This would be a conventional explaination. Red Bull would simply be positioning their tiny legality slot more inboard than other teams.
Two. Remeber the FIA has tightened up the floor vertical tolerance to 3 mm this year. The inboard edge of the horizontal red fin is more than 3 mm above this tolerance zone. Therefore the point where it is connected to the black vertical fin does not constitute part of the floor. This becomes a halfway plausible argument because the abrupt vertical surface it attaches to (i.e. the black vertical fin) can be claimed to not be part of the floor. If the inboard end of the red horizontal fin simply transitioned back down to the floor then this argument would lose out at that transition.
For possibility two, Red Bull would be arguing the opening is a slot in the floor that happens to be enclosed by a vertical fin that is not part of the floor. This would be using the floor vertical tolerance "against" the FIA, clever. This would seem to open the door for all kinds of floor openings as long as they abut to vertical surfaces.
Sorry for awkward wording. Not arguing in favor of RB, just putting ideas out there.
This is a very good explanation, and it highlights the big risk. If this interpretation is indeed legal, then it potentially opens the door for other holes in the floor, could we suddenly see double diffuser reappear? Probably not. I suspect this loophole will get closed, it would probably be beneficial for Red Bull to accept that and change their design in a few races time.