3-1 is an exaggeration, but e.g. in Wisconsin 2018, Democrats won 54% of the popular vote and ended up with only 36% of the state assembly seats:
https://www.reddit.com/r/VoteBlue/comments/fwa7sa/regarding_...
https://www.reddit.com/r/VoteBlue/comments/fwa7sa/regarding_...
(and 50% of seats are not even a majority)
Another model would require 15% more to go from 36% to 51% of seats. In this case, 69% of popular vote (54+15) would be required for a majority of seats, or in other words: 2-1. Which effectively is just as egregious as 3-1.