So far, whale casino is the most popular on telegram casinos as far as I know, and it's only a while they started operating, so, I believe it's too early to begin to think that they would really want to get into any trouble with any customer which could daint or worst still, damage the reputation they are currently building.

I've played on this casino in previous times and had no issues with withdrawals, though my withdrawal amount was way less, but still, it came through all successfully all the time I requested one.
So, I believe the cancelation of the user's withdrawal request isnt something to worry about, like you said, it happens often times when traffic is high, maybe the system is built and programmed to automatically take such action in such circumstances, which is understandable, so let's hope the request will be successfully completed on this second trial.