This article explains what is and isn't allowed. I also learnt from it that the front suspension of the Haas car is bought directly from Ferrari...
https://www.motorsport.com/f1/news/rivals-call-for-haas-ferrari-relationship-investigation-1019469/
I think eyebrows would have been raised based on the fact Haas seemed like the 4th best team in Australia anyway, but it's very telling that the appearance of the designs are also
very similar. It is very difficult to justify how an entirely different design team would come up with exactly the same solutions / ideas / concepts in every design element without some information crossing from the Ferrari team itself.
If I were at Haas, I'd quickly be reminding people that the focus shifted from the 2017 car to the 2018 design very early last season...