I was wondering the same thing. I found this explanation in the Community section from another jam:
Hope that helps!
Viewing post in Can someone explain raw score adjustments and score
That's very helpful.
After a quick scan of results, it looks like submissions with 41+ ratings have a raw score == adjusted score, while 40- have changes, which makes it seem like the median is 41.
So, let's take Fey and Druid Essentials, with 39 ratings as a test case:
score: 3.826
raw score: 3.923
Using the formula from that other post ( "raw * sqrt(ratings / median)" ) we get sqrt(39/41)*3.923 = 3.826
Hmmm, does it work for Isle of the Bleeding Ghost (40 ratings, 3.875 raw score, 3.827 adjusted): sqrt(40/41)*3.875 = 3.827
OK, two data points, that's good enough for me!