This seems kinda unethical. This will just result in some developers at Discord spending time creating a solution to detect such abuse, or everyone will just lose unlimited message history. Of course, anyone offering a service with storage like this should expect this to happen eventually, but trying to take advantage of it in a way that wasn't intended doesn't sit right with me. I sorta understand making some proof of concept of this, but why make official "Disbox" accounts here on HN and GitHub for your service that will surely get blocked soon?
Your website even says "As free as it gets. No ads, no subscriptions, and no fees. All of our features are free to use, forever.". It seems disingenuous to market this as some kind of "service" that will be around forever.