Trudeau was attempting (repeatedly) to interfere in the Canadian justice system for the sake of retaining votes in his home province of Quebec, otherwise an international architectural/engineering firm based in Quebec, which was attempting to blackmail the government, was going to pack up and move to London, England, taking thousands of jobs from the province.
Turns out that Trudeau had selected an attorney general who wasn't willing to play ball. She held her ground and told Trudeau time after time (directly and indirectly) that his attempts to intervene were unethical. She was demoted from her cabinet post and then went public with the details on the political interference in the justice system. Trudeau denied, denied, denied. His story shifted. She released an audio recording that made it crystal clear she was telling the truth.
Trudeau is now paying the consequences. His poll numbers are plummeting. Whether that holds until October, when the next Canadian federal election will be held, remains to be seen.