Research shows that immigrants tend to bring their prejudices with them, adopting the anti-immigrant sentiments of their new hosts. Middle-class immigrants may fear a loss of status. Others simply seek to distinguish themselves from a stigmatised group.
Depending on where they’re immigrating from, there can be bigotry internal to the source culture that they bring with them. For example the Indian caste system. From the outside we just see people from India, but there’s a ton we’re missing.