C. F. Keil and Franz Delitzsch on Hosea 4:9

Hos 4:9 “Therefore it will happen as to the people so to the priest; and I will visit his ways upon him, and I repay to him his doing.” Since the priests had abused their office for the purpose of filling their own bellies, they would perish along with the nation. The suffixes in the last clauses refer to the priest, although the retribution threatened would fall upon the people also, since it would happen to the priest as to the people. This explains the fact that in Hos 4:10 the first clause still applies to the priest; whereas in the second clause the prophecy once more embraces the entire nation.