R' Moshe Yehuda Ashkenazi, Chief Rabbi of Poland, ABD Brisk and Yerushalaim - Correct dependency of R' Moshe Yehuda Ashkenazi

I am NOT very fluent in the subject, but I will try to see a reason. There are a few possibilities to explain these seemingly contradictory sources:

Sefer Yochasin and Hevel Hakesef could be accidentally omitting to mention R' Zvi Hirsch between R' Ephraim Fischel and R' Moshe Yehuda in their genealogies. Such omissions occasionally occur in ancient genealogical sources.

It is possible that Geni is wrong and R' Zvi Hirsch is not really part of this family line. The sources in Geni sometimes contain errors.

Theoretically, R' Zvi Hirsch could be a brother of R' Ephraim Fischel, not a son. This would explain why Sefer Yochasin and Hevel Hakesef do not mention him as an intermediate link in the descending line.

R' Zvi Hirsch may not be Cohen, even though Geni classifies him as such. This would also explain his omission from the Cohenim sources.

In short, the sources appear to have some sort of inadvertent error or omission. Without more information about R' Zvi Hirsch and his life, it is difficult to say with certainty how to resolve these discrepancies. But since Sefer Yochasin and Hevel Hakesef agree and are reliable traditional sources, they are probably correct in this case.

I hope this helps to clarify the discrepancies.

Many times in rabbinical literature there are books that for various reasons omit a generation, and in other books this generation does appear (as in this case)... I don't see any problems with that