The center-line cooling system layout is possibly one of Renault's Achilles' heels, not only in terms of reliability but also in terms of chassis performance. (It's just a theory)
When one retains a concept for so long -and Enstone likes to keep the same concepts 20 seasons in a row, one can stagnate and lose ground at that area.
The Renault center-line cooling system (let's call it CCS) is pretty unique in the paddock. Viry made very laudable and useful efforts to lower/flatten and miniaturize the engine's intake plenum in 2018 and 2019 so that the Enstone guys can put the CCS behind the driver and above the engine... it's a cool layout and it's good for weight distribution since all that weight is placed close to the 'center' of the car...
But what about the center of gravity? Bob Bel admitted in 2018 that this system raises the CoG but he said that the aerodynamic gains it brings (thanks to narrower sidepods), compensate for that... but is it still the case?
What about drag? is this system good for aero and especially for the rear wing? It requires that very large 'air box'/roll hoop.