Earlier quoted context omitted.
Oregon just got a new House Rep member, and if you look at the new maps it has created, its pretty obvious this isn't a one party problem.
Gerrrymandering indeed has a long history, and it's a bit like nukes - if the other side is already using them, it's hard to hold off on your side. In 2018, North Carolina saw 50% of the vote go to Republicans, but they received 77% of the Congressional seats. A couple rounds of that is a recipe for a permanent minority for the other party.
This is really easy to sanity check. For example CA, the best known blue state in the nation. 2020 elections, 79% of the Congressional delegation is D, while only (edit) 66% of the popular vote went for (edit) Ds.
But, but, but, the other guys are even worse than us. We won't stand for truth, fairness or justice, obviously the correct course of action is to out-foul them whenever we can. And then we wonder why the country is on the brink of an ugly divorce.