With @xavigazquez providing us beautiful rear-view shots from Australia, we can use them to get a better visual analysis of diffuser keel geometry on the Top 4 cars in 2025. Photos are arranged by my estimation of diffuser keel drag, but they also correlate to current WCC standings among the Top 4
The vertical kicks were first introduced on RB18 in 2022, and you can read more about them in this thread ->
https://x.com/AeroTechVH/status/1870068370734735406
These have since proved to be a very tricky geometrical feature to make use of in generating good and stable aerodynamic load on the floor. Ferrari had big issues with them on 2024 Barcelona-spec floor and have since removed all kicks they previously had, choosing to rely mostly on tunnels to provide the aerodynamic load.
I have also included horizontal thin blue lines to show a small local suction generated by mandatory transition radii between different surfaces on the floor and I believe the load generated by these also depends on the load generated by neighbouring kicks. So basically, these have a different influence level on every car

McLaren have found a way to control these vertical kicks and the downforce they generate across various ride heights. This is the big tricky topic, as massive kick surface can generate massive downforce peak that disappears if the kick stalls locally - while also leading to high-speed bouncing that Ferrari struggled with.
I believe this floor design is part of the reason McLaren exhibits lower Top Speed figures, both with and without DRS, compared to rest of Top 4 cars.

Mercedes are doing a similar thing, though having a much narrower central keel kick section which reduces the downforce and drag, but also reduces the risk associated with this design. Together with less loaded Rear Wing, it's not surprising they have higher Top Speed than McLaren, despite running larger Beam Wings

Red Bull had a hybrid keel design on Day 1 and 2 in Bahrain test and they switched to kick-less design on Day 3 (this may be the other way around; RB did not provide details on which floor is which of course). With kick-less design of the keel, they only have side vertical kicks on the central boat section

Ferrari SF25 has a diffuser not too dissimilar to final SF24 spec, but they did re-introduce a small central kick on the keel fin - which is now thick enough not to be considered a simple fin anymore. They also have no vertical kicks on boat section, just a small lateral kick which generates secondary downforce increase on the floor tunnel locally