Maybe, but I don't think this significantly harms Trump. Heck, who'd have thought a man found guilty of rape(admittedly in a very, very dodgy civil trial) would be leading in the Presidential polls. Yet, here we are. If anything this helps Trump imo. Depending on how the judge and Biden camps(one and the same thing imo) plays this it could easily help Trump massively in November.
Sure, independents don't like corrupt politicians. They also don't like corrupt prosecutions. It's all about narrative now. Trump dictates and shapes a narrative like very few politicians can. If I was to predict who shapes the narrative better, it's Trump all day long.
I am making no predictions about short term polling. These things are worthless. It's all about election day and the month or three leading to election day.