The Orange Emperor has a huge hard on to make Ukraine suffer ever since it led to his first impeachment. Zelenski didn't kiss the ring so down they go.
If you look at the full list (available e.g. here https://www.newsweek.com/trump-reciprocal-tariff-chart-20545...), some countries (most prominently Russia) are not on it. Whether that means anything is debatable, but Mexico and Canada, who were explicitly "spared" from these tariffs (but have other tariffs "tailor-made" especially for them), are also not on the list.
The Orange Emperor has a huge hard on to make Ukraine suffer ever since it led to his first impeachment. Zelenski didn't kiss the ring so down they go.