It isn't just on Trump either. Kamala has to defend her former liberal policies in CA, defend the current Administration that is one of the least popular on record, and try to explain how her new policy is different.
Americans are deeply unhappy with the current administration. She is part of that and she still DEFENDS the current administration. It's going to be hard to convince Americans it is going to be any different or get any better with her at the helm. Another point that Trump gets to hit her with, is that she has had 4 years to help implement policy changes and only now does she plan makes changes if she becomes POTUS? She has the influence to get things like no tax on tips on the floor for vote right now. Why isn't she doing it?
Don't forget she will have to explain to the American people why she lied about Bidens mental health for years.