We’re in a weird place right now where the national polls are looking better for Biden but the swing state polls are still looking pretty bad for him. However this looks to be the same polling outfit that showed close races in the rust belt trio.
I’m not skilled enough to offer a thorough explanation for this, but I still feel better about Biden’s chances compared to a few months ago.
It's not that hard to explain.
Democrats in 2016 and 2020 had a PV advantage. Clinton won the PV with 3% while losing the EV. So it would make sense that a narrow EV win for Trump would likely have a Biden PV win.
Especially since a lot of states keep trending D like TX long run and aren't going to return to Bush margins.