+13 is probably a big stretch, but FL has been polling VERY well for Biden, with more than a bunch of polls in the 6-8 range for him. I think we may be underestimating how badly Trump/DeSantis are screwing the virus up in places like this.
And this poll is underselling Bidens margins, considering most of the undecided/other vote comes from young people and black voters
No.
how is not? most of the undecided vote is among black voters (they have 10%+ undecided), and the 18-34 vote has "12% other" which also will likely not bear out.