A historian, most well known for being confused with a terrorist who used David Mayer as an alias and placed on a US watchlist: https://en.wikipedia.org/wiki/David_Mayer_(historian)

A US politician, the mayor of Gloucester Township, NJ: https://en.wikipedia.org/wiki/David_R._Mayer

A rich guy, David Mayer de Rothschild: https://en.wikipedia.org/wiki/David_Mayer_de_Rothschild

So, ChatGPT could be trying to prevent giving terrorists publicity, could have some prohibition against discussing political figures, or (probably most likely IMO) could have prohibitions against members of the Rothschild family being discussed to prevent it from spreading conspiracy theories.