Why is no one interested in switching to Audi?

Esteban Ocon has known for sure since Monday: there is no future for him at Alpine and so the Frenchman must look for a seat elsewhere. Audi are reportedly interested in the one-time GP winner, but Ocon himself would prefer Haas F1; the smallest team with the most modest budget and no factory team. Ocon is not the only one who is not hot for F1's newest entrant. Carlos Sainz is also not eager to switch to Audi. Why is that?