I see. Honestly, I feel scammed because the IRCC's very first reply to me explicitly stated that there was no need for special permission to take the oath from outside Canada anymore and that I was approved to take the oath from outside of Canada. That is, they explicitly told me that they approved me taking the oath from outside of Canada. However, my oath was an in-person oath and I believe that this was a possibility only for video oaths. I guess that in the meanwhile, they changed their policy and now they require special permission for anybody that wants to take the oath from outside of Canada. So, I'm stuck in a non-routine application now.
Had they initially told me that taking the oath from outside of Canada was not possible, I would have came to Canada to take my oath. So I feel very misled here.