This is an official government warning confirmed by the Deputy Prime Minister. From the source:

Asked why the guidance had been updated, Canadian Deputy PM Chrystia Freeland told reporters in Atlantic Canada that the government employed experts “to look carefully around the world and to monitor whether there are particular dangers to particular groups of Canadians”.

She declined to comment when asked whether there had been discussions with the US government before making the change.

GO. It’s a Federal Government department that is jointly run by the Minister of Foreign Affairs, the Minister of International Development, and the Minister of International Trade. Putting out travel advisories is part of their mandate.

Most Canadian GO follow a [Purpose] Canada naming scheme. If you want a SIN (equivalent to an SSN) you got to Services Canada. You get your weather warnings from Enviroment Canada. Drugs are related by Health Canada. Natural Resources Canada does the obvious. Parks Canada does National Parks. Transport Canada does highways and waterways.