Look at third parties and their success in the UK and Canada.
The last general election in the UK was 2019. Conservatives got 43.6% of the vote but 56.2% of the seats. Labor got 32.1% of the votes and 31.1% of the seats.
The biggest national third party, the Liberal Democrats, got 11.6% of the vote but a mere 1.7% of the seats.
In comparison, look at regional third parties. The Scottish National Party got 3.9% of the vote and a whopping 7.4% of the seats. Irish regional parties like Sinn Feinn and the Democratic Unionist Party got a combined 2.3% of the seats with a combined 1.4% of the seats.
Previous elections have been quite similar. In 2015, the far right UKIP won only a single seat after getting a whopping 12.6% of the vote.
Canada is quite similar. The Bloc Quebecois consistently gets more votes than the national New Democratic Party, despite having gotten less than half as many votes.