I don't know about Canada, but I can tell you how it'd work in the US and UK.
If you lived south of the border they'd almost certainly keep your old name on the report for at least several years, maybe even longer. Some people have reported (edited to remove a link that is no longer valid) that they've been able to use the dispute process to remove the name once they have no active accounts under it (don't even try if you still have activity that would be under your old name, since it will come right back), but others have tried that and said it didn't work. Unfortunately, the only way that you'd have an actual defense to remove a name is if you've never used it to obtain credit. In any event, you will lose any history prior to the name change if you do successfully get the old name removed; which means that unless you've just come of age, moved to the country (credit reports generally do NOT carry over when you move internationally), or it's been longer than the 7-10 year time frame that information shows up on your history since your name change, your history (or lack thereof) will raise eyebrows in of itself.
For most people changing their name in the UK, and for TSs before they passed their Gender Recognition Act a few years ago, the above procedures would be similar. However, the aforementioned Act has a special provision that requires the credit bureaus there to remove names changed due to a gender transition that are no longer in use by the person in question.
For you in Canada, I don't know if they have any special laws in place for TSs or not in this regard, but if you do look into that. If not, then what I said about US credit reports would probably be similar to what you'd experience.
