Okay, the core point here is that Biden's tariff policy towards one particular nation raised average tariffs on US imports by less than 1 percentage point. It might have been questionable economic policy, but it at least ostensibly targeted a geopolitical rival and sensitive sectors.
Trump's proposal would raise tariffs by at least 10 percentage points, which would obviously be much more impactful. It would target America's allies and adversaries alike. It is basically guaranteed to trigger widespread countervailing tariffs against US exports.
For all the potential faults of a Harris government, declaring a trade war on the rest of the global economy was not on the agenda.