"Canadians might go to bed Monday night without knowing the final results of the federal election. They might not even know who won by Tuesday morning. That's because this year, Elections Canada isn't counting hundreds of thousands of local special ballots, votes from Canadians living in their ridings who opted to vote by mail, until Tuesday.

"The returning office has to go through a set of verifications before they even open a ballot envelope to put it in the box," said Elections Canada spokesperson Diane Benson.

Those verifications include making sure those who voted by mail did not also vote in-person on election day. "Only after that will those ballots be counted," said Benson. "So it could be Wednesday, Thursday, Friday … because it depends on the volume and it depends on how long it takes to do those verifications and then the count."

https://www.cbc.ca/news/politics/vote-counting-elections-canada-2021-1.6179742