Polling couldn't account for Comey reopening the investigation plus a historical lack of excitement on the Dems side for Hillary. The reverse is going to happen on the Republican side for Trump, plus Democratic excitement to vote Trump out has shown in spades in the midterms and in primaries. Trump's going to face a historical defeat in November as he should.
Additionally, polling never showed anywhere close to this large of a lead for Hillary in any of the swing states nor this level of disapproval of Trump for independents. He's going to have an impossible time winning if he can't get more moderate support on his side between now and November, which is why his strategy of embracing the confederate flag/rejecting racial equality movements and pretending COVID doesn't exist over the last six months is easily the most baffling political strategy in US history.