Sara Gideon was favored to win the Maine race in the polling, because there hadn't been a single poll showing Collins in the lead since July. She lost her race by 9 points.
It's also strange to see the region makes a difference in the poll error. The polls in Minnesota were basically spot-on, but in Wisconsin (demographically very similar), the polling average was Biden +8, with one ABC news poll showing him +17, the kind of outlier result you'd expect with a +8 average. He's gonna win there by ~1 percentage point.
There's something wrong with how a lot of these pollsters determine samples, or how they judge someone's likeliness to vote.