The insistence on electoral districts.
You get that across the English-speaking world, though. The really weird thing is that even people who see the problem want to keep the districts and argue for non-solutions like ranked-choice voting.
Centuries ago, it made sense. Communities chose one of their own to argue for their interests in front of the king. Which communities had the privilege? Obviously that's up to the king to decide. Before modern communication tech, it also made sense that communities would be defined by geography.
Little of that makes sense anymore. When their candidate loses, people don't feel like the 2nd best guy is representing them. They feel disenfranchised.
It used to be, in the US, that minorities - specifically African Americans - were denied representation. Today, census data is used to draw districts dominated by minority ethnic groups so that they can send one of their own to congress. This might not be a good thing, because candidates elsewhere do not have to appeal to these minorities or take their interests into account. Minorities that are not geographically concentrated - eg LGBTQ - cannot gain representation that way.
The process is entirely top-down and undemocratic. Of course, it is gamed.
Aside from that, the mere fact that representation is geography based influences which issues dominate. The more likely you are to move before the next election, the less your interests matter. That goes for both parties. But you can also see a pronounced urban/rural divide in party preference. Rural vs urban determines interests and opinions in very basic ways. Say, guns: High-population density makes them a dangerous threat and not much else. In the country, they are a tool for hunting.