Looks like Merc sacrificed some pace in Abu Dhabi in order to run some 2021 items for the post-race test.
Modification made to Merc's front suspension for Abu Dhabi (a test item for 2021):
"As shown in the illustration above, a change has been made to the anti-roll bar connecting rockers, which strays away from a shape that’s been used for several seasons now, in favour of a smaller and more lightweight solution.
The catalyst for this change is likely to do with the incoming regulation changes and the new tyre construction being introduced by Pirelli for next season. The difference in construction not only means the shape of the rubber is slightly different, but it also alters the way you build core temperature within the tyre and how you look after the tread platform."
"Interestingly, the change in tyre shape for 2021 may force Mercedes to make further alterations to its front suspension too, as the upright extension that it has used for several years places the wishbone in close proximity to the tyre’s sidewall.
In preparation for this, it has sleeved the end of the upper wishbone with a polystyrene cover to prevent damage when testing the new tyres. This also allows the surface to be shaved away by the tyre, giving a clear indication of how close it can position its wishbone before it fouls the tyre’s sidewall."
And some more info (new radiator layout, lower PU mode used, etc.):
"Meanwhile, it’s believed the team also installed the experimental radiator layout that was briefly tested on Valtteri Bottas’ car at the Sakhir GP, owing to the same rear bodywork and cooling outlet being selected as was used in that test. It’s understood that this new layout was designed to work in conjunction with next year's power unit.
Therefore, to maintain reliability, the team was likely forced to run in a lower power setting than would ordinarily be the case. This was perhaps underlined by the Mercedes pair being the slowest in the top speed trap during the race."
https://www.motorsport.com/f1/news/merc ... t/4930906/