That sounds like a neat feature but I can't support the backend behind it :D. I would need to rent a server which needs to have protection against too many requests and everything as well as the framework to process the requests. So it's easier to have users press S or make a screenshot with a tool and upload the screenshot to Discord with a quick message.
Hehe, well, easier for you, sure, but not easier for the user. I would assume most people would not want to leave the game and do all those things. It also require that you have an account with Discord etc. You would hardly need a whole server for such a simple feature. I would assume there are even free "contact form"-like services where you could post the input to, which sends you an e-mail. Maybe even Zapier would support such a simple use-case. Then it would even be able to post it to Discord automatically. Anyways, obviously up to you :)