The banning of TikTok on government devices was a decision made by the Treasury Board CIO of Canada, based on an aggregate risk level that was deemed too high. From a government perspective, the aggregation of all that information could potentially expose who our contacts are within government and our activities within government. I suspect that, from a privacy perspective, this is what led the CIO to promulgate the policy around banning the application from government systems.
On November 20th, 2023. See this statement in context.