In a blogpost on RaceDepartment user SalamanderSoldier claims Codemasters used a slightly refurbished 3D model version of his noncommercial F1 Ferrari F2002 mod for Assetto Corsa in their F1 2017 game.
Other users got themselves access to the wireframe model used in F1 2017 and compared it to the AC mod:
Limited slip differential lock if old
UPDATE: He got a reply from Codemasters and posted in the comments without updating his blogpost:
SalamanderSoldier said:Now looking at the wireframe was a dead giveaway that it was indeed my model F2002 that I worked on for months. I could see all the choices this artist made that nearly matched all the same choices I made. My heart sunk and I felt disgusted. So the only thing left to do is contact the artist that and await a response. Days go by with no response except that the Artstation page is now taken down. I've received no response by either the artist or Codemasters as of this time.
Other users got themselves access to the wireframe model used in F1 2017 and compared it to the AC mod:
Limited slip differential lock if old
UPDATE: He got a reply from Codemasters and posted in the comments without updating his blogpost: