More details came out about her firing. Her "controversial takes" were revealed and to say the least,, they're nothing but. Not a surprise but she isn't anti-semitic, in fact she defends the Jewish people in a lot of her quotes; additionally, she's even spoken about getting support for Jewish people on her account.

More info that came out is that Spyglass called for her firing, Paramount most likely approved it. No matter what, they're both equally responsible. 

And remember, do not blame any of the cast or people working on the movie; including the director Christopher Landon. Christopher Landon has made a statement regarding what happened and one can say he is saddened by Melissa's firing.