This is a recurring pro-Kremlin disinformation narrative about Western countries, Canada in particular, as US vassal states. Pro-Kremlin outlets often use this narrative of different countries being under the American thumb to imply that their national sovereignty is under threat and that they have limited power. It is also often used to drive wedges and foment tension between allies.
Canada, like the US, is a sovereign country and makes sovereign decisions about its own security and politics. More about US-Canada relations can be read here and here.
The disinformation claim distorts Justin Trudeau's comments about the plan crash. Trudeau said that escalating tensions between the United States and Iran were to blame for the downing of a Ukraine International Airlines flight in Tehran. "This is something that happens when you have conflict and war: Innocents bear the brunt of it. And it is a reminder why all of us need to work so hard on de-escalation moving forward, to reduce tensions and find a pathway that doesn't involve further conflict and killing." Iran has admitted its responsibility for downing the Ukrainian jet.
For similar disinformation cases, see for example claims that the US regards the EU as a protectorate, that the EU is a servant of US geopolitics, that Japan is not fully sovereign, that Germany is a vassal of the US and the executor of US hegemony over Europe, and that G7 countries are either insignificant or not fully sovereign.