Hi @Pari
As you have given the Grenzübertrittsbescheinigung to the border officer, then there is no issue. The Grenzübertrittsbescheinigung is sent to the immigration authorities as confirmation that you have left Germany before the deadline given to you. There are no further consequences such as an entry ban.
I am not sure what, if any, effect your refugee status in Canada will have on a future asylum application in Germany. I have tried to find some information on this but could not find anything regarding people who have a refugee status in a non-EU country and then seek asylum in Germany. Within the European Union, the rules are very clear. If a person has received a refugee status in one EU country, an asylum application by them in another EU country will be rejected as inadmissible. I do not see any similar such complication in your case but you will be questioned in detail about having left Germany for Canada when you have your asylum interview.
Best,
Éanna