4/4
Here, the top (simplified) drawing illustrates the 2018-2020 layout (the CCS -in pink- hangs above the engine), while the lower drawing shows the 2021 packaging (the CCS becomes bigger, to free up some sidepod and floor space, and moves backwards), so the team had to split the compressor duct (blue) in two ducts, and spread them, to pass the CCS duct in-between
it's a modified @albrodpul drawing
---> This RS19 tub was tailored for the 2018-2019-2020 cooling system, not the 2021 one. And Alpine didnt want modify their tub in 2021, so they had to "cobble together " those solutions under the engine cover, to integrate the 2021 system without touching the tub, and those workarounds made the engine cover wider.
So why did they change their 2018 to 2020 cooling concept in the first place?
It seems the previous CCS could cool the ERS AND some of the engine coolant. So they've probably increased this ability in 2021 and made the CCS cool even more engine liquid in order to shrink the sidepod rads. So this new CCS could no longer fit in the usual location, so they moved it to the rear.