The adjustment is based on median number of ratings. Superstars typically don’t represent the majority of the entries collecting votes. As an example, the largest jam we’ve hosted collecting over 160k total ratings, with many entries collecting hundreds and even over a thousand ratings, has a median number of ratings of 16.
https://itch.io/jam/gmtk-2023/results/top-marks
I’d assume they’re slightly in favor of the developer
This is debatable, the increase attention of a page may skew the voting bias of a rater to lower. In my experience, once a population size increases outside a core set of fans into general audience, you attract people who are more likely to casually rate things very low.