Why were the northenners conserened about the number of representitives southernd states had in the US of representitives?

Northerners were concerned about the number of representatives Southern states had in the U.S. House of Representatives due to the Three-Fifths Compromise, which counted enslaved individuals as three-fifths of a person for representation purposes. This gave Southern states a disproportionate influence in Congress, as they could count a significant population of enslaved people towards their representation. Northerners feared this would allow the South to dominate legislative decisions, particularly on issues like slavery and economic policy, undermining the interests of free states.