Yeah but this has excactly happened again to me, already for the second time. The update was 60 MB in size. Old Kunos skins, old previews, soundbanks destroyed. ****!
I also had an update of about 60MB. It seems that the skins on the 488 Challenge Evo have been replaced. I don't know if that was related to this Ferrari Challenge. I have not been able to find any other "damage" so far.