[WEB-2481] Username bug with redeeming gift cards/ Username blocking

EDIT: I found an explanation on how it's possible to abuse this: https://www.youtube.com/watch?v=dojcW7xYznM

Hello,

I'm not sure if this is already known, but there are currently bots which can block MC usernames for all users. Example usernames:

They should be free, but nobody can take these names because they are currently being blocked by these bots to sell the usernames later.