In Yevamot 76b Avner is said to have reported a tradition that female Moabite converts are allowed to intermarry with regular Israelites.
Doeg raised some reasons not to accept that tradition.
Then, according to tractate Yevamot 77a it was Yitra Hayisraeli (II Shmuel/Samuel 17:25) who is called by the nickname Yeter Hayishmaeli (I Divrei Hayamim/Chronicles 2:17) who informed the congregation that the prophet Shmuel/Samuel had already ruled, that only male Moabites could not intermarry with regular Israelites. But female Moabites are permitted.
But the Talmud itself raises a difficulty how could we believe Yitra (Yeter), since he had some personal gain for his own marriage by this ruling.
The Talmud doesn't present this problem as a knockout question, but only as a difficulty which we might be able to resolve.