The difference between 2016 and 2020 is pretty simple if you compare this poll to the late June 2016 Q-poll.

% of people who feel STRONGLY unfavorable about a candidate in June 2016:

Clinton: 50%
Trump: 48%

and in July 2020...

Biden: 31%
Trump: 53%

— David Weigel (@daveweigel) July 15, 2020