See Rashi Yevamot 78a
להם הלך אחר פסולן - תרי להם כתיבי ומשמע הלך אחריהם דאם נטמעו בכשרים כגון מצרי שנשא ישראלית וישראל שנשא מצרית הלך אחריהן והולד פסול עד דור שלישי:
Mitsri who marry Israelite woman or Israel who marry an Egyptian woman, the offspring is pasul to go in Kahal up to the third gerenation. There are kiddushin and there is Avera the newborn takes the status of the pasul.
For Mitsri of first generation and Mitsrit of second generation, there is a Machloket Amorayim in Kiddushin 67a. The rule is that the count follows the more pasul. In our example the newborn will be a second generation and not a third.
So for a Levi also that is an Avera. This Halacha is strange because even if one of the father is not a convert generally the child is not a convert. Even for Cohanim, the son of a Cohen with a convert is a Chalal. And here the son has a status of mitsri. May be that regards only the count to reach the Heyter Bekahal. But from the pshat Hapashut of the Gemara, it seems that the child is a Mitsri simply. So he cannot get Maaser. He has a status of convert. Please if I'm wrong send me a comment.