CFIA has posted the attached notice pertaining to flexibility in ingredient declarations brought about by substitutions due to supply chain issues.
In a nutshell, if the disruption is unanticipated, you can proceed with a substitution for a short period of time without modifying your labelling provided the substitution does not itself introduce an undeclared allergen or any other health concern. It is understood that the substitution would be for a short period of time, following which you would return to the former ingredient or would be required to amend your labelling to reflect the new ingredient.
If it is anticipated, then you will be required to modify the label to accurately reflect the change in the ingredient declaration.
Below is the link to the release:
I trust this is to your satisfaction. Please feel free to call if you have any questions.
Have a great day and stay safe,