Rav Naḥman says: Those who eat something else, a euphemism for pork, are disqualified from bearing witness. This is referring to those who accept charity from gentiles, thereby causing a desecration of God’s name. They are tantamount to wicked people guilty of monetary transgressions, as they are willing to desecrate God’s name for monetary gain.
The Gemara comments: This statement applies with regard to taking charity from gentiles in public [befarhesya], but if one takes it in private he is not disqualified. And even if he takes it in public, we said that he is disqualified only in a case where he can sustain himself by accepting charity from gentiles in private and despite this he disgraces himself by taking it in public. But if he cannot support himself in any other manner, he is not disqualified, as it is his livelihood.
Rambam as translated into English at https://www.chabad.org/library/article_cdo/aid/1178799/jewish/Edut-Chapter-11.htm accepts this statement of Rav Naḥman as halacha.
Here is a quote:
Similarly, base people are disqualified as witnesses by Rabbinic decree. This refers to people who walk through the marketplace eating in the presence of everyone, those who go unclothed in the marketplace when they are involved in ignoble tasks, and the like. The rationale is that they are not concerned with their own shame. All these people are considered as dogs; they will not be concerned with testifying falsely.
Included are those who partake of charity given by gentiles in public. Although they could derive this benefit in private, they denigrate themselves and accept it in public without showing concern for their honor. All of these individuals are disqualified according to Rabbinical decree.
So too, Shulchan Aruch, Choshen Mishpat Chapter 34 Halacha 18 accepts the statement of Rav Naḥman as halacha.