From the Hutter Prize FAQ:Why do you grant a 'discount' of 5'000 Byte per day?
The contest went big early 2020, but so far no-one was able to beat the baseline. The discount has been introduced to ease participation and guarantee eventually at least one winner. The discount is around 1.5% per year, so should allow a first winner within a year, or at most two. The reason for the incremental discount is to prevent a quick win by whoever notices the discount first.