Ok - if your employer knows that you will be physically present in Canada the whole time you're working for them in the US payroll and they have no objection then I guess there isn't anything you can do.
Technically, there are guidelines from the Canadian revenue agency, the CRA, that requires that a non-resident employer (e.g. a US based employer) withhold and remit Canadian taxes to CRA (just like IRS expects US taxes be withheld for those employed in the US). This is a legal requirement under the tax treaty. It is an employer's obligation. And failing to meet this, they can be penalized by the CRA/Canadian government. Due to this, most established companies will not let you be on the US payroll (as a direct employee) and be fully remote in Canada. Hence, most people either transfer to a Canadian entity of the US company, or are employed through a PEO, or become independent contractors. Do you work for a large established organization? e.g. Microsoft, Apple, Google types? If you work for a small organization with only a US footprint, they may not be aware of these requirements. I work for a US headquartered international firm, and their lower level HR people did not know the answer to this either. I had to ask them 2-3 times, and they escalated internally to their legal/tax compliance department who then provided me with a detailed response.
The employee obligation (i.e. yours) is still the same - you file your Canadian taxes and declare your US income. If CRA pays attention and realizes that you were drawing income from US, but your US employer did not withhold and remit any taxes to them, they can take action.