There is a reason, that I am not so sure as some here, that Biden wins, and we have another news to further my suspicions: https://www.theguardian.com/us-news/2020/sep/28/us-election-observers-europe-latin-america
Also, with increased number of mail-in-votes there is the strong possibility, that these votes will be attacked afterwards as invalid, if it helpsTrump. In my opinion there is the clear possibility, that no clear winner can be declared or the result is strongly challenged. That is something the model of 538 isn't calculating: https://projects.fivethirtyeight.com/2020-election-forecast/