With the release of improvements to the avatar system and changes made to accommodate the avatar sales system,
the issue of inconsistent performance rankings has worsened.¹
There are now
three
separate ranking stats shown for a singular avatar, and
only one of them is correct.
Take the details from the pictured avatar. It is of "good" rank, on PC, and Poor rank on other platforms.
According to VRCHAT.com, it is poor everywhere, and even worse, the Performance Breakdown in the UI ranks it as Very Poor on all platforms. This is significantly incorrect.
With the introduction of the ability to find and purchase avatars in-client,
it is imperative that users know what they are purchasing. An incorrect ranking could severely impact a creator's ability to make sales, as users may incorrectly trust these metrics, and pass on avatars that have been erroneously ranked between 1 & 3 ranks worse than they actually are.
  1. https://feedback.vrchat.com/bug-reports/p/performance-rankings-are-not-consistent